Ubuntu – Why does 11.04 freezes randomly

11.04freeze

We're running Ubuntu 11.04 on quite a few Dell machines, but I am noticing that on some of them (including mine) Ubuntu freezes on randomly.
Normally when the screen goes to lock mode and you press a key to wake it up, this will happen.

Only mouse cursor can be moved but nothing else can even be clicked.
The only way out is to either go to terminal with CTRL + ALT + F1 key and re-login, or do a hard shut down.

Has anyone else also seen this happening?
What's the cause and solution/prevention!?

Best Answer

I've seen this happen a few times. When it happened to me, it looked like Unity's compositing manager just stopped drawing the screen for some reason.

As an alternative to restarting my session, I switched to a terminal like you did, and then ran the following:

DISPLAY=:0.0 unity --replace

That got everything drawing again. It is possible that you could just blindly run unity --replace from the Alt+F2 prompt in this case too, but I haven't tried that.

I haven't done any investigation myself about the underlying cause though.

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