Ive had a problem with flash player in the past on a few PCs Ive repaired for people, websites said I needed to install/update flash player, it would then say its updated but the website would keep saying needs to install/update.
I cant remember exactly but I think the problem was some instant messengers using the files, it wouldnt let the program update properly so although the installer said it updates it doesnt actually update, hence why the websites keep saying install/update. Likewise if the programs are in use (even running in background) it wont let you uninstall via add/remove programs, itll say its removed but the files are still present on the pc as they are in use, when you install flash again it still doesnt overwrite the files because they are in use and you are back to square one.
I used a specific uninstaller from Adobe website in safemode and reinstalled flash, seemed to do the trick once I had worked out wtf was going on