GUI Not Working Correctly

[Andy Collins]

I have downloaded the rc version of dapper (by mistake) and when i put 
it in and reboot, X doesn't seem to be configured right. I get a 
"multicoloured" screen, squares that i cannot do anything with (if i hit 
alt+ctrl+backspace ubuntu seems to try and take me back to the GUI, in 
which i get the same result). Anyone know how i can fix this?

Sorry for the very poor description of what happens, but i find it hard 
to put into words.

Thank you
Andy