It's possible the driver was corrupted.
Did he drink too much? xD
Anyways, back to topic:
I would try to
- use an image restore or a system restore point
- try the options to not check for rootkits at start up and to load Avast Services only after the other services
- check the
S.M.A.R.T values with
CrystalDiskInfo- use
chkdsk /f /r (it might take a few hours, so do it when you don't need your computer for a long time and be sure to backup any important data) and
sfc /scannow in elevated command line to check and repair possible drive and Windows code integrity errors
- do a boot-time scan
Else, you might consider buying a good Solid-State-Drive or mSata-SSD instead of your old HDD to boot from. It's really worth the money for the comparable less space provided.
p.s.: I would also consider calling an electrician to do a current check. In the worst case, you might also need to switch power supply and/or motherboard and/or other components, too. Also, just to make sure: you don't plug the PSU along with all kind of other things on the same power strip?