gnome desktop not working

I have a 10.10 installed on my home PC and was working fine until a few weeks ago. The desktop is now not working. When I boot after loading a notification says

"Install problem!
The configuration defaults for GNOME Power Manager have not been installed correctlyh.
Please contact your computer administrator."

And then there is only black background. The only way I can access or work on anything is through the Cairo dock I luckily installed. Although I may be able to work on some files like watching video or so through Cairo (click on the application on Cairo and use the menu bar of the applicaton), I can't copy files (nautilus doesn't seem to be working) so that I can format it. I tried to update using synaptic but oddly it won't let me in even though I gave the right password. Terminal also doesn't work. I just want to backup the files so I can format it and install 12.04.

Any help is appreciated.