I wanted to file a bug about this using ubuntu-bug xserver-xorg-video-intel, but the system prompted my to try posting here first. So here goes :-)

While the situation in Ubuntu 11.10 was still somewhat workable (see UI freezes when disconnecting DisplayPort), in 12.04 (using Unity 3D) it has gotten worse.

The weird part is that during the 12.04 beta's, the situation was actually improving! I was able to successfully connect and disconnect a DisplayPort monitor without the system breaking down on me. But now with 12.04 final (with all updates), it's just plain terrible.

When I now connect an external monitor using the DisplayPort connector on my HP ProBook 6550b, it only works sometimes. Most times (but not always!) the screen just goes blank and the system seems to crash (not even CTRL+ALT+F1 works anymore). Only a hard shutdown by keeping the power button pressed for several seconds and then a restart gets me out of this.

I suspect the chances of the system crashing become higher as the system's uptime increases, especially when there have been one or more suspend-resume cycles (although I have also experienced this bug once from a cold boot).

Disconnecting is roughly the same as with 11.10 (see issue mentioned above), with the difference that if I resume from suspend, I no longer have to do a CTRL+ALT+F1, ALT+F7 cycle to get my screen back.

So what more can I try? Or should I just go ahead and file the bug anyway?