We have got an installation of Outlook 2010 that corrupts every .pst archive opened with it, except for a newly created test archive which only had one mail in it.
All archives cannot be opened and give a message stating the archive ist corrupt, and afterwards, that error persists even for other installations, with the notable exception of the one mail test archive, which can still be opened by other outlook installations, but not this one.
Old friend google comes up surprisingly blank on searches, so I'm a bit stumped.