yea, thats the jest of it. the default themes that came with gnome/ubuntu randomly disappeared...i simply turned my laptop on one day and they were somewhat gone...i think i may have installed some updates that it prompted me to install the previous day. from the Appearance Preferences, i can't choose any new themes (because there are no themes listed except Custom), or modify my current one (features such as changing the colors are grayed out, but some aspects of my current theme are incorporated into the GUI).
i used apt-get to uninstall and reinstall the package gnome-themes and gnome-themes-extra, and it did nothing. After installing a new theme, it is not listed in the theme tab.
i'm not really sure what other information is needed for you guys to help me with this, so if you need any please ask
oh, im running ubuntu 8.04 and Gnome 2.22.3.