I am having some trouble with backtrack 5.I installed it from a backtrack 5 live-cd,and at the end of the installation,i had a message when i reboot,i don't know if it was normal.It was somehing like "Radeon...unable to allocate GEM"but itt was longer than that.(the message was repeated cvery fast so i can't read it easily)
So when i try to boot ubuntu from grub,i enter my login/password,and then...black screen!My computer keep running,but my monitor is going to sleep.
I ry the recovery mode,and i launched failsafe graphic mode,which didnt worked.it said "graphic acceleration issue".I try to log the issue into a file,but i don't think it worked.I didnt find the xorg_backup_file.

WHat can I do?

My graphic card is a radeon 5400 series,i have the last driver installed which is Ati Radeon Mobility HD 2000/3000/4000/5000/6000 (drivers 11.7 WHQL).

Sorry for mistakes.