Well, I'm not sure if this problem is related to PDM5 or not, but it has started to appear after installing PDM5. What happens is that, oftenly (not always), when the computer comes back from sleep or when I try to unlock the screensaver ('Require password to wake this computer from sleep or screen saver' option is set) the logon box briefly appears then goes away (Parallels isn't running). In an occasion it didn't come back (the cursor was visible), and teh machine had to be forced to shut down.
