Pro Tools 7.4 Error message! Help!

[mark sounds]

I just upgraded to Pro Tools 7.4 LE. I have a Powerbook G4 laptop. Run ProTools with an original Mbox. I have 13 gigs available on my computer's harddrive and I run my sessions off a firewire 400 drive with 400 gigs available. G4 has 1gb RAM and 1.5 ghz powerpc processor.

As far as I can tell (from the spec requirements on the digi site) my computer is compatible with the new version. I keep getting error -9136 (Cannot get audio from USB audio drives fast enough. Remove some plug-ins or delete some tracks.)

Here is the thing. I am not running an excessive number of tracks or plugins. Nothing that I havent done before with much less free space on my computers harddrive. It has even happened when there was only one track in the session (just a stereo mix of a beat) with no plugins on the track, no aux sends, etc.

I've already increased my buffer size, playback engine, all that to maximum.

Any help anyone can give me is appreciated. Thanks!

[nicpope]

that always happens to me when I try to run a session off of my firewire drive.
sorry man.

[mark sounds]

i updated my os and it solved the problem. my old one should have been compatible but whatever works.

[mark sounds]

So everything seemed to be running smoothly. Updated to Mac OS 10.4.11 My sessions were running ok for a couple days, now it's happening again. Error with sessions containing only one track, no plug-ins, etc. Any help?! Can my computer just not keep up with the new version of Pro Tools?