sure.... so your saying
Mac Book Pro, has been upgraded to 22.214.171.124 and NO problems
Mac Pro, was a clean install to 126.96.36.199 and has problems (with Midi crashes)
ok, so go to /Library/Audio/MIDI Drivers/
In there you will find : Virus TI MIDI Driver.plugin
tell me that date and size of this for both the MBP and the MP.
also, as mentioned in the first post, on your MP go check the console (details in the above post) and see if you can find a MIDIserver crash file,
and if it looks similar the one at the top of my post.
THEN... if you feeling brave
on the MP, copy the Virus TI MIDI Driver.plugin somewhere safe (you can get it back, but easier to know)
then copy the Virus TI MIDI Driver.plugin FROM the MBP to the MP, to exactly the same place
restart the machine, and see if it helps. (in particular the test cases I list at the top... I cannot say this is the cause of ALL issue, just the ones I've encountered)
(but still let us know time/sizes ... as then we can see if the MBP had the 5.0.8 driver, or the 5.1.0 driver)
Im assuming Access will be trying some fresh installs, and also some upgrade installs to help determine if this is a possible issue,
and then advise us... the slight issue is 188.8.131.52 is no longer on the beta downloads, luckily I found a copy on my Time Machine