This seems to be happening with nVidia graphic cards to fix this problem try to use the following solution i hope this would help
I have a HP Pavilion SLimline s7727c
with lspci giving me
VGA compatible controller: nVidia Corporation C51 [GeForce 6150 LE] (rev a2)
I was getting a blank screen (out of sync) on booting from the live cd.
I worked around the problem as follows:
* At install screen press F6 and select nomodeset and install Ubuntu as usual.
* On first boot after install, press e on getting the GRUB bootloader.
* Using arrow keys navigate to and delete quiet and splash and type the word nomodeset in their place
* Press Ctrl and X to boot
* You should now be able to login to your Ubuntu as usual
For those of you who do not know what to do next, in the taskbar click on System->Administration->Hardware drivers, and select and activate the nvidia current driver if you have an nvidia card like I do. The driver will be downloaded and activated automatically, and you will be prompted for a reboot.
Yes, I think you may be right about it being a graphics card problem. I think you may have the same problem that I did on my beat-up old Toshiba Satellite A10.
So, here is what should work:
At the very first screen, the one with just the rectangle (it's meant to be a keyboard) and a human figure, press any key -- spacebar will do.
Then choose your language.
Then make sure you have "Try Ubuntu without any changes" selected, and then press F6
Add this to the end of the command line:
Then press enter and it should boot successfully.
1. Boot from the Ubuntu 9.10 CD
2. Mount the internal HD and look for /etc/X11/xorg.conf -- its missing!
3. Copy a new "known good" xorg.conf file to the HD (I had to use sudo cp ... otherwise I got permission problems)
4. System boots fine.
Thanks to ubuntuforum user for this solution