Right, I have Ubuntu 12.04LTS installed on my Compaq laptop. I originally installed at around v11 and upgraded whenever it suggested that I should. I have custom, unsupported Wifi drivers that I reinstall every time I rebuild the kernel through an upgrade.

The problem is that occasionally, it logs out straight to the log-in prompt, purple screen. It kinda freezes for a second, then goes, even with the drum noise. The only trigger I can identify, is that it's usually when I'm typing. Sometimes in a box for Hotmail, sometimes on a forum, occasionally when using Office.

I've tried changing from XUbuntu to regular, and tried logging in using XCFE, and Gnome and regular Ubuntu but it keeps happening.

Any ideas?