I have a Samsung Series 9 laptop, model NP900X4C. For a long time now this laptop has had issues with the battery and AC adapter, like this, which got fixed about six months ago: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/971061

Ever since I upgraded to 14.10 I've had a lot of problems, but the most problematic is that I can no longer unplug or plug in the AC adapter while the system is running. If I do, it simply freezes. Mouse stops responding, keyboard stops responding, everything else appears to stop responding. Just completely freezes. Nothing in any of the logs in Log Viewer. Removing the adapter (if plugging it in was what froze the laptop) or vice versa does nothing. The only way to get it to respond is to hold the power button to turn it off.

If the laptop is suspended or hibernated, I can unplug or plug in the adapter and the laptop will work normally after resumed.

I've tried with both the bundled charger and a third party charger, to rule out problems with the charger. Same effect.

Does anyone know what could cause this?