Hello BC!
On Vista, I have just recently hooked up to the Internet. For security, I have installed McAfee's Internet Suite (yes, I properly used the Vista installer off their website: it itself works fine). Though on my dad's PC, his computer hasn't had any issues, mine gets angry at me fairly quickly. Upon booting, I can only start Firefox or IE once. If I close out, then reload the browsers, nothing comes up, and multiple browser processes spawn in my processes in the Task Manager. My computer then refuses to restart, so I have to tell it to do so manually.
Both browsers have also had issues loading webpages, as well.
-Glen

I would first suspect either a corruption of the McAfee Internet Suite or a malware infection. Even with a security product installed, you can still get infected easily - so I'd suggest these free, online scans to double check your system:

http://onecare.live.com/site/en-us/sandbox...s%2Fdefault.htm
http://housecall.trendmicro.com

Another thing to try would be to TEMPORARILY disable the McAfee to see if you can connect then.

EDIT:I had originally posted that disabling McAfee had solved the problem, but right after I said that, it came again! It seems to happen after the computer has been on for about 7-8 minutes, and makes all Internet-related programs freak out, as well as the Shutdown/Restart buttons.
I will restart into Vista (I'm typing this in Ubuntu), and try both scanners again.

Well, I found and removed a likely culprit: DSSAgent.
Came with a few Carmen Sandiego games. So far it has seemed to do the trick.