Windows Crash/lockup

I have a problem with one of my office machines, it has been working fine up until last week when the machine will, when left unattended for couple hours, not wake.

I generally leave this machine on over weekends so i can remotely connect from home when i discovered i could not reach it as it was shown as offline, i went to office to find pc powered but display in standby and would not wake. I eventually have to force shutdown by holding power button then machine will immediately reboot & function fine. Will sleep and wake OK during day hour or two at a time but if left for several hours or overnight wont and im not sure the best way to go about debugging this.


Have checked event viewer and some errors do show but these occured approx 30 mins before machine going offline where there are entries for services shutting down. No minidumps generated so its not blue screening and i havent made any system changes or installed/uninstalled any software other than win updates, what can i do to trace the source of this problem

Machine is running win 7 32bit

Thanks Paul

Ok so i had a good look through event viewer and the only critical or serious errors related to the forced shutdown/reboot so no clues there, have checked temperatures and all seem normal so doesnt appear to be heat issue, not sure how best to go about tracing the root of this problem

Any input gratefully received