I recommend windows 7 or 8 too.

Before you try and upgrade the OS, try rebooting the machine all the way. That means turning it off wait about 10-15 seconds, and turn it back on again. This solves about 90% of the issues a lot of people deal with, but not all of them.

If that doesn't work, try flushing the cache. To do that try the helpful guide DocJohn supplied in a sticky here in this forum. I'll try and find a link to it if I can.

Alternatively, it could be a malignant process running in the background, or some malware you might have picked up at any point in time. It happens even if you're super careful. If you still have the black boxes coming up on this site after rebooting and flushing the cache, try running your antivirus program. I'd recommend a full scan, just to be sure it looks in every last nook and cranny of your HDD and beyond.