Apple Logic Pro /LogicExpress Discussion

Hi, group.

I'm having a problem with Logic Pro 8 quitting unexpectedly. It always  
quits on "Initializing CoreAudio." I've done everything but swap  
machines here; tried it under OSX 5.6 and 6.2, reinstalled the system  
(clean install) and reimported from a known good backup (I know it was  
good because the drive was taken from an iMac G5 where Logic worked  
fine). All the usual, lesser solutions of course: repaired  
permissions, reset the program when offered in the "Unexpected Quit"  
dialog, trashed prefs, sacrificed a ram, etc.

Any idea what I can try? In case it's informative, Garage Band won't  
run either. GB's startup sequence is much less informative  
("Initializing Garage Band" without details) but it eventually either  
quits while unresponsive or I have to force-quit. Any connection?

Thanks.

Bobbo