So the Smart testing is saying the hard drive itself is OK.
Then it is another issue causing the trouble if it acts up again.

If it does, the next things to look at would be the
windows operating system - may have gotten scrambled - a reinstall would fix this is you have the CD or the restore disks

or
some other mechanical /hardware inside the laptop is failing - this is hard to tell , the easiest way would be if a re installation of windows is done and the problems continues, then that would more or less show something is wrong with the internals of the laptop.

Thanks, Jo*mar! The next restart may tell me something.

As one of my instructors told me a self test only proves a certain level of capability at that time. It does not prove reliability. Long story short this seems to be an intermittent problem, the worst kind.

I put my money on a malfunctioning controller in one of the primary subsystems. How old is this PC?