I have a Mac which regularly runs into a problem. The user interface stops reponding, showing a "frozen" user interface. The mouse is still moving but clicking does not trigger anything. This happens about once a week. Solution so far is to force switch-off the Mac and reboot it.
I have ssh root access to the Mac. Killing (kill -9) the active application has no visible impact on what is shown on the screen.
Any ideas on how to diagnose this?
Is there a way to restart the window manager from the ssh shell? Killing /System/Library/Frameworks/ApplicationServices.framework/Frameworks/CoreGraphics.framework/Resources/WindowServer seems not to be possible.
The Mac is an early 2008 iMac and runs Lion with latest updates. /Library/Logs/DiagnosticReports is empty.
Problem stays after update to Mountain Lion.
The WindowServer process is in "uninterruptible wait" state ("U" flag in ps output set):
imac:~ root# ps ax|awk "NR==1|| /WindowServer/"|grep -v awk PID TT STAT TIME COMMAND 86 ?? Us 50:51.69 /System/Library/Frameworks/ApplicationServices.framework/Frameworks/CoreGraphics.framework/Resources/WindowServer -daemon
Any idea for diagnosing what blocks the process?
Any idea for "waking up" the process?