So how long does it take to determine you have something really wrong with your computer?
A couple weeks before Christmas, I started having issues where my computer became very slow and started flipping back and forth between open applications. Going off of John's issues, i thought it might be my power supply because I had some loose wires. I finally ordered a replacement power supply (twice because the first one as a generic ended up not being able to supply enough power).
The new power supply works great, but I still had the problems. So I did the last option as a PC owner.
I reformatted and re-installed windows.
I've been doing that since New Year's day, and I've almost got everything back to the way that I wanted it.
It certainly does help you clean out the programs you don't use anymore.