Itunes intalling on Dell...trouble with 8.2.1

Have been using I tunes forever and when I updated from 7.6 to 8.2.1 on my Dell Laptop has been nothing but grief. No matter how many times I reboot, reinstall, un install, or even try to re install 7.6 I always get the message cant find Itunes folder necessary for operation of I tunes. The normal default location for this folder is My Music folder. It has been installed there and Ihave tried to continue to install it there. Its one of those "Look in there you stupid computer"...sorry for being synical but its just so frustrating when I have a better than average understanding of computers. HELP!!!