after i researched this issue for several days and i emailed apple support this is what i did and it really worked. somewhere i saw on a post to download revo uninstaller because it gets rid of all aspects of a program. i downloaded the revo uninstaller pro. you get a 30 day free trial. i uninstalled everything apple. there is a place on there where you check what scale of scan to use. the first time i used medium on the first few items and advanced on the rest. the advanced scan really went through each and every file after the so called uninstall and found traces of the programs. i had to check boxes beside files that had traces and removed them all. (I ended up having to do this twice because the first time i did this the error box kept popping up when i reinstalled, so my advice is to choose advanced each and every time. also after the first time, that box popped up during the reinstall of itunes that said i needed permission to install something.) Next thing i did was checked on the recent updates and installs on my computer. windows/ms had installed 3 things in those automatic updates. i uninstalled all 3. i'm convinced that there is a corrupt file in there somewhere. there are several fixes and scans on the left side of revo, and i ran several of them just to check. the final one on the bottom was an evidence remover. since everywhere i have seen says to remove all traces, apparently when you empty the recycle bin it really doesnt get rid of it. so i did the evidence remover. it took all day. almost 9 hours. next, apple support had suggested i go to windows update site and download the latest version of there update software. i was wary, but i did this update. i restarted my computer. next i went back to apple and reinstalled itunes. during the reinstall, the box that said i needed permission didn't pop up. after the install the error box didnt pop up. and when i went to itunes, everything was there. i cant tell you which exact step fixed it, but something did. good luck to you. i emailed the apple support guy back and mentioned the revo uninstalled. i'm pretty sure that advanced scan really did the better delete than just uninstalling.
Lynne