Computer keeps turning itself off completely

[Sherbert37]

Had some problems and it went away for repair. Cost a fortune and the guy wants £60 to step over the threshold so want to see if there is some easy solution (hopeful emoticon).

He thought there might be a problem with the hard drive but there wasn't.

Sometimes it will run for ages before turing off, other times it does it quickly. Any ideas?

does it feel overly hot when it shutdown, if yes could be overheating (had this with one of mine once, the fan was fine it was just blocked up), opened up and gave a clean and all was well.

My vote is for dusty fan too.
Give it a blast with the hairdryer through the side vents so you dont force the dust further in.(Or vacuum cleaner to suck it out)

Alternatively you may be blocking the vents with clothes etc when using it. Its set to shut down as soon as it seems its overheating for whatever reason.

Thirdly ( but less likely)you may have a virus.Just do a search for the symptoms+virus on google and see what comes up.

Thanks all. Was a dusty fan last time (sounds rude that). Was persuaded to get a wireless router so the pc is not on all the time. Will blast with hairdryer.