I got stuck trying to help a customer tonight. She had an old version of some software installed (it was migrated somehow from her old WinXP machine to her new Win7 machine).
When she went to install a new version of the software, it went into Program Files (x86) just fine and the file sizes and dates looked right. However, when double-clicking the application icon, the old version came up.
We went round and round uninstalling, reinstalling, deleting, etc and every time the old version came up even though Explorer was showing only the new version. It was like Groundhog day.
It's as if the old version was still there hidden in the Program Files (x86) folder.
Finally, I tried dragging the folder containing the software out from under Program Files (x86) to the root of C: and the new version came up just fine. She's happy now, but the software is in the root of C and the phantom version is still lurking in x86. I expect if she gets an even newer CD some day, the old version will rear its ugly head again.
More about :weird windows file behavior duplicate hidden
It's the weirdest thing. The shortcut points to the file that I can see in Program Files (x86) which is the new version but clicking the shortcut somehow brings up the old version. It's like there are multiple versions in the Program Files (x86) folder but I can only see the new version.