Odd - can you send me the crash reports? You can find them in either: ~/Library/Logs/CrashReporter/ or ~/Library/Logs/DiagnosticReports/ (where ~ is your user folder) Any files in those folders that begin "MixEmergency" would be of interest. If you're unable to find your Library folder (it's likely hidden), then just go to the Finder, in the menu bar select "Go", and then "Go to Folder...", and then enter "~/Library" and push enter/return.
