Weird Behavior--need some diagnosis help

[imported_blip]

I'll try and lay out what happened:

Last night, my internet starts crawling, and eventually just won't find a signal. Today, I unplug and restart my modem and router, and things seem to be back to working as far as the internet is concerned.

I go to start surfing, and things are frozen. I figure it's just from messing around with things, so I restart. As windows is about to begin, my monitor goes off. It doesnt lose power, it just acts as though there is no signal coming into it. The computer is still running. I don't think windows even started, because when I hit my computer's power button (which is set to shut down the computer properly) nothing happens. I hit the reset button, and the comp shuts off immediately. Fan goes off, etc., but the green light on the front stays on. ?

After restarting, it starts up, then freezes after a minute. I restart, monitor goes black. Shut down. Give it a minute. Restart, and things have been working fine since.

Any ideas what's going on? I thought it might be the PSU (350W, I forget the brand. Starts with an 'A' but isn't Antec), or maybe overheating? I ran anti-virus stuff and nothing was found.

Thanks for the help!

 

[Lord Evermore]

Video card.

 

[Atheus]

What are your temps and voltages?

 

[imported_blip]

My video card is a 5500fx, and I've never had much problem running games, let alone just surfing and such.

I don't have any temp/voltage software installed. Any suggestions? Is there any utility for this that comes standard in windows? Or do I go through the BIOS?

 

[Biggerhammer]

My PC did some things similar to that, turned out to be vidcard overheating. Check that the vidcard fan works and isn't jammed up with dust.