Computer unable to recognize wired network connection

[DerMaus]

I built my first computer a while back and have been using it with only minor issues, the greatest of which is the collection of dust. This thing has been able to take everything I've thrown at it, but for the past few days I've botted it up to find it has no internet connection. The motherboard has a built-in network card (I assume, again, first computer), and plugs directly into the AT&T box in the next room that everyone else has no issues using, including my wirelessly-connected laptop. Last time this happened I just waited a few hours and booted it up again to find the problem had resolved itself, but this time I had to reset my motherboard to get it working. Any suggestions to prevent this from continuing?

--UPDATE--

I shut down my computer for the night and started it up today to find the problem is back again. This time the computer connects to "Multiple networks" (not the single box the cable is connected to, but generic "Network" and "Network 2" instead), but is unable to get through that network to the internet. Restarts, hard restarts, motherboard restarts, ethernet cable changes, port changes, safe mode startups, a 6-day system rollback, and an afternoon spent reorganizing my room did absolutely nothing. I finally got connected by rolling back my onboard network card and then updating it again, but a restart sent me back to square one.

[concerto49]

Prevent dust? Get a decent case - not a dust collector (i.e. not those "uber gaming cases"). Get dust filters if required. Don't open up holes. Solved. Just get proper cooling if stock cooling is an issue.

[Naaz]

[QUOTE=concerto49;39446808]Prevent dust? Get a decent case - not a dust collector (i.e. not those "uber gaming cases"). Get dust filters if required. Don't open up holes. Solved. Just get proper cooling if stock cooling is an issue.[/QUOTE]Probably won't help.

[DerMaus]

[QUOTE=concerto49;39446808]Prevent dust? Get a decent case - not a dust collector (i.e. not those "uber gaming cases"). Get dust filters if required. Don't open up holes. Solved. Just get proper cooling if stock cooling is an issue.[/QUOTE]

I'm OCD so having a dust-preventing system was a really appealing idea, but the problem is in my house; the ventilation system has no exhaust, so the entire house is one massive dust trap. But I can't imagine dust being the exact cause of my network connection problems.