Well everything sounds like it should be OK, (although I don't really understand the 96kHz/latency relationship).
I used VST5 on a P233 and got over 10 tracks of audio out of it, so the only thing that I'm thinking is that you're using too many plugins/EQ/dynamics and that this is putting too much of a load on the CPU.
One solution would be to mix down each track(channel) with the FX and load them up into a new song. Thus, having them sounding the same without the plugins.
Even now with a more powerful Mac, I sometimes run into the same problem on SX. This doesn't degrade your recordings, it just means that the PC's just having a hard time.
Generally, I say nothing to the band. Bounce down things like drums, bass, rhythm guitar and create a simpler song file, with less plugins, to allow me to finish recording. Then I sort out the problems afterwards...