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SystemUIServer process freezes indefinitely (resulting in ostensible system freeze), cannot be quit

SystemUIServer process freezes indefinitely (resulting in ostensible system freeze), cannot be quit

CNET staff
2 min read

We are beginning to investigate an issue where the SystemUIServer process, which is responsible for various Mac OS X interface components -- hangs indefinitely, resulting in a complete ostensible system freeze. By ostensible freeze, we mean that while the standard user interface is frozen and no functionality can occur (the cursor is still movable), the system still functions normally via other means of interaction including SSH sessions.

MacFixIt reader Marc offers a case example:

"Four or five times, now, the graphics on my original MacBook have frozen. The interesting thing is that the cursor still moves around with the mouse. The machine is still happily up and running, too, but the graphics are frozen such that all i see is what was up when the freeze happened.

"For me, it seems to happen when i hit command-tab to switch applications. Unfortunately, I can't seem to be able to reproduce it this way. it happened to my co-worker on his MacBook Pro a couple days ago when he clicked on a dock icon.

"When it happens, you can ssh in from another machine and the machine appears to be running fine. What you can't do is kill the SystemUIServer.app process. It is obviously stuck waiting on a kernel call that never returns. Not even a kill -9 works. "

On numerous occasions we've covered troubleshooting issues where killing the SystemUIServer process can prove helpful. We've also covered situations where the SystemUIServer process hogs an inordinate amount of processor resources. However, we've yet to encounter a situation, as described by Marc, where this process cannot be quit.

One potential method for obviating this problem is to delete the file com.apple.systemuiserver.plist located in ~/Library/Preferences/, though we don't yet have confirmation of success with this procedure.

Feedback? Late-breakers@macfixit.com.

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