Display crash on user change

[D3m0n1q_733rz]

After being logged in as a user, if another user decides to attempt to change user as guest instead of entering a password, the display will sometimes go black and fail to respond resulting in no signal to the monitor. The only known way of fixing the problem is by restarting the computer.
If another display driver such as the ATI driver is used, this error results in the inability to start X and crashes upon entering the startx command. I believe that this error is the result of attempting to reset display parameters prior to bringing the display adapter back online on user change. The result would be issuing commands to an interface which was not yet available to receive commands.

Ubuntu Version: 12.04 with proposed updates enabled

The error can be recreated, but I can not seem to generate a program crash report to submit here.

[Ubuntu Foundations Team Bug Bot (crichton)]

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[D3m0n1q_733rz (cryo-rebirth)]

Eh, I'm not sure. But I'll go with it.