This may be a completely unrelated issue, but the fact that Logic 2 had stopped some time during a 48h run could be caused by this issue I brought up a while back: I2C Analyzer hoarding temp-files - especially if you were still running with the analyzers attached.
I experienced similar symptoms when running (i2c) analyzers because of a bug that caused Logic to not free up the memory from old temp-files (as long as the app is running) would completely fill my hard drive and cause Logic to crash. I experienced this frequently because my hard drive was already running out of space. If you were running for 48 hours I imagine even a fairly large hard drive would have time to fill up.