I've had a couple of complete system hangs on two different systems in the last couple of weeks. The first time it happened I shrugged it off, but now that it has happened a second time on a different system I need to investigate this a bit. further All the systems are identical: IBM (Lenovo) ThinkCentre M52 with 3GB of memory, running CentOS 4.4 with all the recent updates. The systems are currently running the 2.6.9-42.0.3.EL kernel (IIRC, the first hang happened with the 2.6.9-42.0.2.EL kernel). When it occurs, the system is completely hung. Whatever was on the screen at the time continues to be displayed, but the machine doesn't respond to pings (so you can't ssh into it), the mouse is frozen, you can't get to the alternate consoles (Ctrl-Alt-F1), etc. In other words, the only recourse is a reboot. There is absolutely nothing in /var/ log/messages or any other log files that I could find after the reboot. In both cases, the users report that they were editing a file when it happened (they weren't even trying to write out changes to disk). Anybody else seen anything similar to this? Any recommendations on how to capture all relevant information should this occur again? How would you debug a problem like this? Alfred