I installed the new 2.2.2 code (note I've never installed the older code) on a fully-patched Windows XP machine.
I get a notification that setup cannot continue because some system files are out of date. At the time I selected to update them, and the install completed and everything worked.
It should ask you if you want to keep the current files, in which case you should. This happens on every install. Keep current files and ignore any errors and it will install properly.