Advice, please, on a weird 'stopping' problem

[sclg]

Just finished rebuilding my PC - MSI K8N Neo2 Platinum + Athlon 64 3500 Venice. 2 x 512 Mb Crucial DDR400 memory(*). Akasa Cooler. New 500W PSU and new SATA Hitachi disk. Using my existing CD/DVD drives & Matrox G550
Reloaded everything - XP Pro SP2, fully patched, AVG and MS Antispyware both up to date.

Twice today, the machine stopped. i.e. appeared to freeze and would not visibly respond to mouse or keyboard.
BUT....
go to another machine on the network and I can remotely access it's drives and files. I can even point 'Computer Management' at it and see that there is nothing untoward in any event logs.
Eventually had to use the reset button on both occasions.

Later, the video went crazy. All fuzzy like it had largely lost sync. Could just see enough to shut it down.Restart and all is OK - at the moment.

Mobo, processor, memory and disk are all about 3 weeks old. Video is a dual monitor setup on a Matrox G550 with the latest drivers.(I've been using this card & set up for some years on various machines)

Have run memtest for a couple of hours with no problems. CPU temp is OK -
upper 40s.

Anyone any ideas??

[nichomach]

Aside from your G550's finally given up the ghost?

[Jonny]

Yeah, I'd definately test another graphics card in your rig. (Rather than test your graphics card in another rig).

[sclg]

Does sound plausible. I've got an even older 450 I could put in!
What do folks recommend these days for a dual head card? (No games)

[Jonny]

An old fx5200 can be got for around £35 and has dual monitor capabilities, plus enough grunt to give you good graphics outside of games. I was using one until recently and it was fine playing FarCry/Doom 3, so desktop apps is easy for it and will be for a while.

[nichomach]

If no games, stick with Matrox; the P650's great, ESPECIALLY if your twin screens are TFTs with DVI.

[sclg]

Thanks