I have been running MAX/MSP very successfully for several months on a group of 4 identical 2 Ghz iMAC G5s. Significantly (as will be explained shortly), I did not try to use any maxj objects.
About a month ago, I installed IRCAM's FTM package on these computers, as well as a 2x2Ghz Power Mac G5 and an 867Mhz Powerbook G4. The FTM objects worked fine on the Power Mac and Powerbook, but not on the iMacs. Once I installed the FTM package on the iMacs, I had to remove the _FTM_.pat file from the startup folder just to keep MAX/MSP from crashing on startup. Even then, when I would try to create an FTM object, MAX/MSP would hang (spinning rainbow pinwheel) and I had to force quit. I spent several weeks posting to IRCAM's FTM forum regarding this problem and tried literally dozens of fixes. Finally, someone suggested that I try to open a maxj help file to see if there was a broader java problem. In fact, when I tried to open any maxj help file (on any of the four iMacs), MAX/MSP would hang (just as with the FTM objects). At that point it became clear that this was not a problem with FTM, and it was suggested that I post the problem to this forum.
Has anyone had a similar experience with iMac G5s? Anyone have any ideas what the problem might be?