For over 6 months I have been having major connection issues, I will outline everything I have tried and hopefully someone with some knowledge of these things will be able to help me because I have run out of ideas.

The problem:
My internet connection drops randomly, when I am browsing it doesn't matter because it comes straight back if I click to go to my homepage. I only notice it because of the little connection icon in my taskbar, the globe symbol disappears and a page won't load on IE. Then I click on "Home" and my browser returns to Google.co.uk and the globe re-appears indicating the connection has been re-established.
When I am gaming and the connection drops, it doesn't come back. I lose connection from the game server and when I return to my desktop the connection icon has a yellow warning triangle in place of the globe symbol and when I hover the cursor over it it says Local Connection Only. In the past I have restarted the PC and router and the connection comes straight back. When it happened today I opened the Network & Sharing Centre and saw the yellow warning triangle on the connection from my PC to the router and a red cross on the connection from my router to the internet. I clicked on the yellow triangle and Windows reset the local network adapter and the connection returned immediately.

My hardware:
Windows Vista Home Premium 32-bit Service Pack 1
AMD Athlon 64 x2 Dual Core Processor 6000+ 3.02GHz
4GB RAM
NVidia GeForce 8800GTX 768MB
ISP: Sky Broadband (10mb unlimited)
Network adapter: NVIDIA nForce Networking Controller
Router: Sagem Wireless ADSL Router (Sky) Firmware: 1.5Sky
(I only have my gaming PC connected and I connect via ethernet, I don't use the wireless)

What I've already tried:
When this started I was with another ISP, I phoned them and they did alot of tests and eventually said that I might be getting traffic-shaped because I had gone over my usage-limit. I accepted this and left as soon as my contract ended hoping switching ISP would solve the problem. It didn't, I still had random disconnects with the new ISP.
A new router came with the new ISP and new cables for the router so that rules out those being the problem. I also changed from ADSL to cable with no change so that seems to rule out any problems on the line or sockets.
I have re-installed Windows Vista.
I have changed filters on my lines, unplugged cordless phones and tried moving the router to different positions incase of interference. I also re-installed new drivers for my network adapter.
The problems still persisted so I phoned my new ISP for help, once again their tests found nothing wrong on the line. Since I had changed ISP and all other hardware and drivers they suggested the problem had to be with the network card.
I phoned my PC supplier and told them this, since my network card is onboard they had to take the PC back to test or change it. They had it for a month and said they could not replicate the fault. In the meantime I used another PC at home connected to all the same equipment the other one was connected to. This one never got disconnected but instead would get a very slow connection especially at peak times, so slow that it wouldn't even load the R2P site on Internet Explorer sometimes. During that time I was able to race but would have to withdraw occasionally because I was lagging too much. However, the fact that I never got disconnected would seem to point to the problem being with my original PC. That was returned with new memory in it (2x2GB instead of 4x1GB, they said 4x1GB had been known to cause issues on some Vista PCs), I think they just did that so they could say they had done something rather than nothing. I have had the PC back for over a week now and had 3 or 4 disconnects during online racing sessions. After today's I have once again gone back to googling the problem without much success, just found a load of other people with very similar problems also looking for a solution.
I have checked and re-checked all the router settings I can, and all my IE options, all my network settings and I can't find anything wrong. I looked at my Event log after today's disco and these were the last 3 entries, the very last being right at the time I got the disco:

3.18pm Certificate Services Error.

Log Name: Application
Source: Microsoft-Windows-CertificateServicesClient-AutoEnrollment
Date: 27/07/2008 15:18:26
Event ID: 64
Task Category: None
Level: Warning
Keywords: Classic
User: N/A
Computer: Daz-PC
Description:
Certificate for local system with Thumbprint 4e 7c 54 42 2a 43 1a db de 20 36 77 0e b2 fa 58 fb 58 cd 44 is about to expire or already expired.
Event Xml:

64
0
3
0
0
0x80000000000000

5154


Application
Daz-PC



local system
4e 7c 54 42 2a 43 1a db de 20 36 77 0e b2 fa 58 fb 58 cd 44

3.20pm TCPIP Error.

Log Name: System
Source: Tcpip
Date: 27/07/2008 15:20:49
Event ID: 4226
Task Category: None
Level: Warning
Keywords: Classic
User: N/A
Computer: Daz-PC
Description:
TCP/IP has reached the security limit imposed on the number of concurrent TCP connect attempts.
Event Xml:

4226
3
0
0x80000000000000

23562
System
Daz-PC





00000000010000000000000082100080000000000000000000000000000000000000000000000000

4.38pm DHCP-client Error.

Log Name: System
Source: Microsoft-Windows-Dhcp-Client
Date: 27/07/2008 16:38:17
Event ID: 1003
Task Category: None
Level: Warning
Keywords: Classic
User: N/A
Computer: Daz-PC
Description:
Your computer was not able to renew its address from the network (from the DHCP Server) for the Network Card with network address 001A92333A03. The following error occurred:
The operation was canceled by the user.. Your computer will continue to try and obtain an address on its own from the network address (DHCP) server.
Event Xml:

1003
0
3
0
0
0x80000000000000

23570


System
Daz-PC



001A92333A03
%%1223

I don't really understand these logs or how to use them, I have tried googling the error codes but that hasn't helped. The DHCP problem would seem to be the cause but is that as a result of the earlier problems not being resolved?
I really hope someone can help me out here, I am pulling my hair out after yet another disco and I have run out of ideas. Only thing I can think to do next is return my PC again but that would mean another month of racing cocked up because I'd be on my old slow computer again and I don't think they know how to fix it anyway.
My connection speed is fine and I can always get my connection back easily by restarting but that doesn't help with online gaming.

Darren :

here is a fix for the first problem in your logs .. looking up the other 2 now

Microsoft-Windows-CertificateServicesClient-AutoEnrollment :

http://technet2.microsoft.com/windowsserver2008/en/library/377fa889-9962-4e68-8b69-9cac9a9d3ab01033.mspx?mfr=true

I tried that myself and although I thought I followed all the instructions exactly it didn't work as described. I am going back to retry it but I don't understand atleast one of the options it asks for so I'll try each option to see if any work for me.

Darren, you said the other PC held connection, why don't you try an additional network card fo r the hell of it, they are cheap or use the one from the other PC, see what happens then.

I suggested that to the PC suppliers and they said that it's not possible to use a seperate Network Card whilst I have the onboard one. Otherwise, yes, I would have been happy to shell out a few pounds for a network card if that would solve the problem.

You should be able to disable the onboard one in the BIOS for the system. Then it will use whatever add-on card you install as the primary interface.

I'm not too sure I'd believe that you can't use another network card - it's just another PCI device after-all and even if you can't disable the onboard one in BIOS, running multiple network cards is often done. I'd be trying it given how cheap they are.

Edit: you beat me Justin!

Darren you can have as many Ethernet cards as your PC can handle. I've done this numerous times, being a tech. Jonty is right it just another PCI card. You dont even have to disable the onboard one.

Its VERY possible to have 2 3 or in some odd cases 4 nics. I've fixed 2 systems that had damaged onboard nics due to lightening this week. I've fixed them by simply installing an ethernet card. All I did was disable the broken one in windows, never touched the bios.

It just reads it as another connection. (Local connection 2 it will be called) Just like laptops that have wireless, wired, and IEE1394. You just cant connect them all to one router or odd things happen.

The only reason your supplier told you you cant is because they want you to buy another motherboard, or even build a new PC, and are taking advantage of you.

Get a 25 dollar ethernet card from newegg or something. I'd recommend the brand Network Everywhere. Its a basic Lan ethernet card from Linksys and it works out of the box and windows finds it no problem. Anyone will do but I've used these and havent gotten a call back saying it shit the bed yet. You wont gain any better connection by buying an expensive one.

Just go into your internet connection and disable the onboard lan, dont worry about the Bios. You'll have 2 mac addresses but if nothing is plugged into the bad one you'll be fine. Infact dont even worry about the Onboard nic just install the new one and leave the other one alone.

Seriously try it.

My brother lost his onbord nic too and has order a PCI nic to sovle his. It was damaged from lightening from the bad storms this pass week.

You could replace the motherboard but, if everything else is working fine then just get a nic, plug your cable in and it just work right out of the box, you dont even have to reconfigure your internet or anything if your using a router.

If that doesnt work then replace the motherboard.

Did you get the Limited or no connectivaty message with the yellow ! symbol?

OK thanks guys, I will bring that up again with the tech guys and see what they say about it now.

If he tells you u cant do that, just buy one anyway. Trust us, they are easy to install. All you need is a screw driver and about ten minutes.