Computer Switching Itself Off
 

Last night, I went out, left computer running- got home three hours later, to find that it had switched itself off. Switched back on, and it remained on overnight, (as usual- I leave my computer on most of the time). Everything fine for morning and early afternoon, other than Firefox switching itself off a couple of times by itself (just upgraded to v14.0.1). Same with Outlook- it switched itself off whist I was in the middle of composing an email. Went out for a couple of hours at 3.00 pm- computer switched itself off again. After a few abortive attempts, (with momentary blue sceen verbage, after which an auto shut-down again), I am now back up and running. Prior to last shut-down, I ran MalwareBytes, computer was clean.

But I don’t know why this is suddenly happening, after over a year with no problems, since I last carried out a re-install. I know that that would fix the problem, but I want to wait for Win 8 in a few months time, before I do the next reinstall.

Anyone got any thoughts? Any advice welcomed.

Check Event viewer, run diagnostics on hard disk for a start.

SD

Also check for dust & fluff inside and around psu fan.

Possible mains power cut? Happens quite frequently to us out here in the sticks.

Download 'Speedfan' and see if you're computer is running at too high a temperature

overheating
or failing motherboard

what make /model of machine?
which motherboard?