I have and early 2009 dual cpu mac pro with 26 gigs of memory and 4 Hitachi 1 TB drives in a mirrored strip set. if i boot it up and shut it down its fine. If i open even safari or the finder and then attempt to shut it down it hangs at the grey screen with the spinning flower. I have booted to single user mode and fsck'd the system. used onyx to clean up crud on the system. even bought mac keeper which appears to have helped the situation but based on behavior i have to run the mac keeper scan and clean things up before i want to shut down the system. I'm running lion 10.7.1 My suspicion s that the mirrored stripes are the root cause but im looking to be sure before i tear down the system and rebuild in a different drive config. any suggestions i would enjoy hearing. thanks in advance for any assistance.