Help! Work PC randomly blue screens

[stoz]

I'm having an issue with my work PC (HP, 64 bit, Win 7, 4GB Ram, 450GB HD which holds OS, program files etc, most docs kept on network) randomly shutting down. I'll leave my pc, come back to it later and find its shut down. Moving the mouse will stir it to life again and it reboots. There is the option to start in safe mode, and then in Windows I get a generic error message about there being a problem, but it doesn't give me much info. Event viewer only says that the previous shutdown was unexpected, there's no app errors or nowt. How can I check WTF is going on with this, as sometimes it happens every evening, sometimes my machine's on for a week before it happens. Cheers

[DrKazza]

could be lots of things... i'd put my money on dodgy memory (or overheating memory).

trivial quickfix may be to open it up and blow out all the dust

[stoz]

Microsoft security essentials hasn't found anything, but unfortunately anti malware bytes has. First step to clean all that up. Pissed off as I rebuilt the machine just before Christmas