GDM freezes system?
 

Before the problem appeared, I had recently switched from KDM to GDM and uninstalled a great deal of kubuntu-desktop. I used to change display managers. The next day after shutting down my HP Pavillion Enterainment PC freezes at "Stopping system V runlevel compatability" or something similar.

I rebooted my Ubuntu system in recovery mode got to a shell prompt and again uninstalled KDM. that allowed me to get to a normal-ish prompt - normal except for the fact that I have lost the framebuffer. I was able to use but once I used and rebooted my system freezes at a different point. I now am able to write to you after I used but then selecting lxdm (I try out lots of software).

The problems that I have noticed as of now include:

1. There is no display manager that functions.
2. The command line framebuffer is gone (text displays unnecessarily large).
3. Unity (2D I think) uses an inferior display quality (lower resolution)
4. There is no sound anymore.

I had similar issues with gdm, especially with gdm3. I suspect it has to do with gdm's starting scripts. I would suggest you try slim as your default display manager, and see if tthe problems you mentioned are still there. It's lightweight and I never had any problem with it. LXDM might also be a good choice in the future, but for now it seems to be on early stage of development, and most distributions don't even include it in their repositories.