Well I have more ideas for you...
If it's project specific you could try backing up the project, bundling the project up, opening the bundle and saving as a project again. And another thing, so you have a saffire. Are you sure what you are hearing isn't coming out of the Mix Control software and away from Sonar. I assume you are running 3.3.
And please check the Windows
event viewer for specific clues to your crash (find the SONARPDR.EXE Crash, right click the red icon, Copy -> Copy Details as Text, paste here).
Thanks..