Might have been CHKDSK running (are your precious files backed up ??), could have
been automatic installation of updates, if you have that feature turned on.
You got so little information its really hard to be any more definite. I suppose
I'd advise to give your PC a good thorough scan for viruses and spyware, look through
the start-up list in msconfig for any unexpected items . . . then relax.
BTW when you say "maintenance apps", what do you mean ?
