As I didn't personally witness the issue, I only have my wife's input to provide as evidence. She was working on her Master's Thesis last night and both of our profiles were forced to log off the Mac. She described it as "working on her Word document and it suddently went to a blue screen where we logon". We were both logged on and had programs running. She had Firefox 2 and Word 2004, and I'm fairly certain I only had Firefox 2 open with a number of tabs. This occurred on a Early 2008 mac pro with 6 gigs of ram. Based on what she described and her not being familiar with how a Mac boots due to our infrequent reboots (we switched in January), I assumed there was a kernal panic and it rebooted. Once I got on the Mac later last night, I saw the uptime was still 3+ days, so a reboot did not occur. For informational purposes, our Mac is scheduled to automatically sleep at night. I checked the CrashReporter logs in both profiles and there was nothing to be found from yesterday. Any ideas what would have caused two profiles to logoff and close everything, but not reboot? I'm new to the Mac and don't know what other logs to check.