FCP7 Reconnect Media Issues after upgrading OS

Question

I've updated a 2009 MAC Pro 2.26 GHz Quad Core Intel Zeon from 10.5.8 to 10.6.8 and eventually want to get to 10.8. (Note - I did not do a clean install.) However, since that update I've had various problems files with MXF and XDCAM files opening or relinking.  I've also had the frustating "General Error" or "Out of Memory" error when trying to open and XDCAM timelines that was created before the update.  
I updated the CalibratedQ Software that is required to play MXF via Finder and through FCP.  I've updated XDCAM Transfer program from Sony along with their new Content Browser from because XDCAM Transfer is not supported going forward to 10.8.   I also tried deleting QT7 and redownloaded it, however that didn't fix the problem.  I deleted QT7 again and took it off another computer that is working fine using 10.8.  Those two things fixed most of the problem with opening files in Finder and in Final Cut - then I was able to play XDCAM and MXF files.  (Note when I did the software udpate after moving QT7, an update for QT brought back my problem of not being able to play XDCAM or MXF files.  So once again I reinstalled the older version of QT7 and will not allow it to update.)
However, as I've proceeded with editing I'm having problems with MXF files again. Some files will play in Finder and other MXF files in the same folder/same directory structure won't play.  When opening a FCP timeline, MXF files that were connected previous to the update won't reconnect.  When attempting to reconnect, it will show me the file in the top window, I can locate the exact file on the drive it thinks it should be, but when I click on the file and hit "choose" it disappears from the upper window and never moves to the lower window for me to hit the connect.  Also, some files, when hitting reconnect, open up the reconnect window, show the folder the file is suppose to be located, but doesn't show the name of the files beneath the folder name. 
I've read a lot of different responses on this topic and haven't found anything that quite matches my issue or fixes the issue.  I've deleted FCP preferences, FCP plist, and thumbnail caches, and tried moving the problem files to a local drive on the computer rather than on our server.  But since I have problems playing some of the MXF files via Finder, it's likely causing the same problem with FCP.
Any help out there?

Answer 1

As an update, I've spoken with CalibratedQ software and found an item in QuickTime 7 that needed to added from Calibrated.  QT will now play MXF files and FCP sees it. 
But this update to different OS still has issues with linking to some files and needing to reconnect, plus I just tried to export a 60 sec video from a timeline in an h.264 format and I'm getting an out of memory error regardless of the fact that there is 174gb available on the drive.