try doing a restore, then see if the file you originally tried to read will just open after you tell Adobe OK on the note that came up. I get those notes ALL the time, no matter what version I'm using and the files open fine.
If you can read the file without a newer version I wouldn't bother installing it again.
The other way you can try is uninstall the new version, then uninstall the older version, then re-install the new version.