[junobear]

I get that as well. I have increased the buffer size to the max, no help. It also tells me to delete tracks or reduce plug-ins. I routinely dump unneeded tracks and the only plug-ins I have are factory installed with PT LE 6.
I also sometimes get this while RECORDING, not even bouncing.

I work on a iBook G3 (900) with 640 MB. There's plenty of room for the tracks I'm using. (spoken word under a minute each).