UBUNTU 8.1 Desktop Edition not running after installation

I am a new Ubuntu user, installing Ubuntu on Windows XP .
The installation process is successful but after installing when I login , it just freezes with a blank screen for both XClient scripts and GNOME sessions.

I have given 10 GB space to the installation.

Also i noticed that the time till the user ID and password are to be entered, the Keyboard works fine, but as soon as the password is punched in , keyboard stops working. During the whole freeze the mouse is working fine and the mouse pointer can be moved around, but none of the right or left clicks work.

For session FailSafe terminal, the command prompt appears and i can punch in the commands there, i also tried running a few inbuilt games there and the keyboard and mouse worked fine in this session. i just don't understand that why the XClient scripts and GNOME sessions are not working and is this something to do with my keyboard.

Please help !!!!

Singla

did you install via WUBI or was this into a 10GB separate partition?

I had the ubuntu installed on a separate 18 GB partition and while installing ubuntu, installer asked me to choose the disk space i want to let go for Ubuntu.
I choose 10 GB at that stage.

Your 10GB space should be unpartitioned. Mean's size you are giving to UBUNTU must be non partitioned space (free). First let this thing sure then see.

Do you mean i need a dedicated unpartitioned hard disk for the ubuntu installation?

I have 80 GB HD and made four partitions out of it.
I am using one 18 GB partition out of those four partitions to install Ubuntu. So this 10 GB which I selected while installing is from that 18 GB partition itself.

yes you should try while doing so... Or install UBUNTU putting CD in Windows running OS. i think you will install when do so..