How to get my desktop back, after a GUI login all I get is a terminal. Unable to start desktop.

This is my second time with this so here goes, I'm running a dual boot dual core 2.3 ghz. 4 gb ram generic Intel/AMD processor machine with 2 internal and 2 ext. HD.

Re-installed the entire OS and all the apps.Rebooted and logged in to a fresh desktop no problems.

Then I un-installed Evolution and installing Thunderbird again and configuring it and updated all the software drivers and software upgrades from the internet using Ubuntu Software Center then reboot againa and it's back to the login gui and when the password is entered all I get is a xterminal window, or a terminal window I guess with the white background, that's as far as I can go.

It's worked well both times until I un-install Evolution. There might be some kind of link between the two.

Thanks,

-Sid

I appoligise for the previous rammbling on and the attitude, It's been frustrating.