For the longest damn time I couldn't figure out what was ailing my comp. My scheduled tasks wouldn't run. I had problems installing certain programs, upgrading some, etc. I finally found out why. If you name your C drive's volume label WINDOWS, and you have windows installed in a folder also named WINDOWS on your C drive, it can cause a conflict. Your OS won't know where to locate some files. That was the case with me. Name it something else, like PRIMARY or something.
Now that I got that settled, I may try to upgrade IE again...or maybe not :-/