Beryl stopped working on Intel Mobile 945

[Boo]

I expect it may be in the "Module" section.
maybe the "load glx" line, you can remove or comment this out. there may be more.

you could reconfigure the Xserver, I think there is a gui to do this in the admin menu.
or
sudo dpkg-reconfigure -phigh xserver-xorg

also check /etc/modules and remove any line referring to nvidia.

[scorp123]

Unfortunately for me, I guess it is a BAD IDEA to mount the linux partition (an ext3 filesystem) from the LiveCD.

Shouldn't matter. In fact many people use Live CD's to e.g. rescue data from their ext3 partitions or to repair stuff.

Because, when I rebooted, that partition was TOTALLY corrupted.

You must have done something else previous to that. Proper mounting and unmounting --Live CD or not-- won't do that. Sounds like you did an unclean shutdown??

[scorp123]

I either did a quit->restart from the menu or a sudo shutdown -r now from the terminal.

Both would be OK and usually should properly terminate all remaining processes and cleanly unmount any mounted disk partitions. An 'unclean shutdown' that will usually cause trouble would be e.g. if you used the power switch to suddenly turn off your machine, or if there is a defective CPU and/or defective RAM in the system and the machine all of a sudden without prior warning crashes (or freezes). That too could potentially screw up your disks depending on what you were doing when the crash/freeze happens.

But quitting via the menu or issueing a proper 'shutdown' command shouldn't do this to your disks ... Maybe your disks just had a bad day or something. I once lost a partition too just by rebooting. I was working in the office all day long on that laptop ... I packed up, went home ... and at home: oooops, all my data was gone. I never really figured out why ... but then again the laptop on which this happened to me is a bit flaky so maybe I was praying to the wrong gods, or maybe some evil spirit got insulted because I did not sacrifice a dozen chicken or something like that before I decided to touch the laptop ... No idea what happened or why. When I came home all data was gone. It hasn't ever since happened to me on that laptop. Sacrificing a rabbit and dancing around naked on midnight seems to help (just kidding here ...). Technology is unfortunately like that. Sometimes it will fail on you even though you did nothing wrong.

Surprised the heck out of me. I've been hacking around with Unix in one form or another for 20 years, and never saw that serious a failure before.

Welcome to the club See above. Happened to me too. And I never really understood why and how this could happen.