Although you mentioned that you have updated the "drivers" on your computer, have you also updated the ethernet drivers? It may make a difference. How old is the ethernet card?
And since it seems to shut down when you're playing games and using the VOIP at the same time, are you sure the power supply is big enough to handle everything running at the same time? 400-500 watts maybe?
What happens when you remove the side panel from the computer tower, then point a house fan at the computer inards? Have you cleaned out the junk/dust from inside the box?
Hope this helps.
I play the world of warcraft and many many guilds are starting to require using either ventrillo or teamspeak to run in raids and I have downloaded both of them in an attemp to get one that works without restarting my computer but both do it. Vent does it immediatley and teamspeak will work for awhile at times before ultimately restarting. I was hoping someone could give me a few suggestions on how to fix this problem. I have alrady reinstalled both of them and updated all the drivers on my computer.