In the process of cleaning up a Windows XP (Home) PC, I ended up with a situation where it would get to the 'Windows is starting up...' screen, and just stay there for 20+ minutes.  Doing a hard reset didn't help; it would boot back to that same spot and just hang there. 

I found this forum post, where they've suggested to plug the PC's power cord directly into the wall instead of a power strip.  Since I had just purchased a new power strip, and then plugged that PC (and another one) into it, I thought I'd give it a try. 

Yeah, it worked.  The PC booted up as fast as XP ever could.  I'm assuming the two PC's together must be drawing too much current for the power strip/surge protector, and so the troubled computer wasn't getting enough juice to boot properly...?