Intel iMac/Pro Tools 7.1 CPU power

I have a brand new iMac, out of the box just last night. I installed 7.1, and it works, no bugs I don't think. However, I tried to bounce a session I already had containing 8 tracks of Audio, 1 auxilary reverb send, and a master fader. The only plug-ins on the whole session are one stereo d-verb plug-in, the digi-rack compressor and 4-band EQ. The playback engine shows the H/W Buffer Size to be 1024 Samples, 2 RTAS Processors, and 85% CPU usage limit. All the same, at the end of the 5:30 bounce, I still got a CPU error! The same annoying one I used to get when I ran too many plugins and the same one that suggests deleting tracks or increasing the H/W Buffer size! What do I have set up wrong?? I don't think this is supposed to be happening... Why am I running out of CPU power?? Any ideas??

Is it an Intel iMac? How much RAM is installed? Did you install ProTools LE 7.1.1 ?

yes, it's an intel iMac, 512MB of RAM and ProTools 7.1

Are you using the same harddrive for both the program and the audio files?

You should have a minimum of 1 gig RAM, prefered 2 gig. The Pro Tools version has to be the "intel version 7.1.1" Separate drive for your audio sessions

Sounds like he's running 7.1 under Rosetta? Remarkable if it even works, especially with 512M RAM. On an Intel Mac, you need to install the 7.1.1 update.