Hmm. what has happened is that your default session is set as terminal rather than KDE/Gnome. Tell you what.
Go to /etc/inittab
search for a line that says id:3:initdefault and change the 3 mentioned there to 5. Next time, when u boot up, it will start in graphical mode, but with a choice of session (and u must logon graphically too). Session choice is usually somewhere at the bottom, you must select it b4 u login. Anyway, once u are logged in, change the default session from your system preferences (search thru the menus for something like login prefences or whatever, varies slightly for each distro). Change the default to Gnome (or KDE), then change inittab back to how it was. Voila. You shud be done. There is a way to do this all from text mode, I am sure, but I haven't learned that yet.
(I think it must be somewhere in the /etc/X11/xdm/ directory, but am not sure).