i had the same issue....
when i looked in my add/remove programs i noticed that there
were two instances - one for adobe flash 9, the other for
macromedia flash 8. I can only infer that it didn't remove the old
version.
i then removed both versions, restarted my machine went to a
webpage that used flash, it prompted me for the download and voila
- success :)
hope this works for you too!