"The audio engine has been stopped unexpectedly"
 
Very frequent, all projects. After it happens, I have to back up the now time to a different spot to resume.
 
Using ASIO drivers, changed the buffer size from 1024 to 2096, and then to 4092 (maximum), still no better. Incidentally, the driver controls are being changed from the M-Audio utility which is only openable from the Windows task bar (clicking ASIO Panel from preferences doesn't work).
 

Click the help in the TOAST message and try some of the suggested remedies.

I had numerous problems with M-audio interfaces. Went through 3 of them in a short space of time. Always dropouts, freezes, corrupted audio. Also, if you havn't already done this, check out Craig's tip as below:
Week 35: Potential Glitch Reduction/Latency Improvement Tip for Windows
 
It would seem to be an audio conflict/driver issue that you are having. Have you tried deleting and re-installing your driver for the M-audio?

What does DPC latency look like on this machine? With very high ASIO buffer sizes (and/or a ton of audio tracks), you may need to increase your disk output (playback) buffer. Does the ASIO buffer really need to be that high for this project? I seldom ran over 512 samples on my old Core2 Quad, and my new I7 machine never breaks a sweat at 128. I've had issues in the past when experimenting with very high buffer sizes.