PC crashes

[Nick]

...and you have tried a different PSU, right?

That's on the list too. Freezes like this can be PSU-related but normally you get some log warning or the BIOS tells you.

The memory one is subtle - sometime the BIOS can get it wrong, even if memtest86+ says the memory is OK.

Doing this stuff remotely is a pain - hanging is normally bus-related , but power can be a problem, especially if you have a lot of devices, like hard drives...

Mark makes a good point - the wattage rating of the PSU might be worth investigating if you've added hard drives or power-hungry display cards. PSUs fail too....