CPU Overload 6101 error

[FutureBC]

I have a mastering project inside ProTools LE 8.0.4, and all was good as of the last time I saved the project. When I opened it up after a few days of not touching it, I somehow cannot play any part of the session without getting the dreaded CPU Overload error. I'm using T-racks mastering software as a plug-in on all the tracks. It was working fine for weeks, and in fact it is working fine in another mastering project I am working on. So how is it that one works, and the other session gets this overload error? The session with the errors has 10 tracks using the plug-in, and the session that is working fine has 8 tracks using the same plug-ins.

I've tried changing the buffer size to the largest (2048), as well as the cpu usage limit. I've also tried changing the DAE playback buffer settings (currently have it set to level 0 with a large cache size), but that didn't help. Not sure what else to try. Any suggestions on how I can get this resolved?

Here are my specs for the system I'm using:
Macbook Pro w/ Mac OS X Version 10.6.4
2.4GHz Intel Core i5
4 GB Memory
ProTools LE 8.0.4

[caruso7r]

Are you reserving any of the processors for other processes in the playback engine?

[DigiTechSupt]

I would try trashing preferences and see if that helps.