Ubuntu 12.10: Cannot get into ubuntu desktop

[safarin]

Hi...

I just do fresh installation Ubuntu 12.10 on entire disk (no dual boot).. but seem I cannot get into Ubuntu desktop... Here the detail..

I installed on Asus K50 laptop.. which have two graphic card Ati and Amd...
Previously I use Ubuntu 12.04 without any problem... and without need to install any additional driver..

After finish install and restart.. I got nothing.. only black screen.. No grub or no Ubuntu splashscreen..

I also cannot access into no-gui session (Ctrl+Alt+F1)...

What have I done:

Try to update and change the grub by using Ubuntu CD..
but get this error
"failed to get canonical path of /cow"

Try using Ubuntu CD then get into nomodeset to install additional driver, but cannot access to the source directory (internet), before that on the splash ubuntu screen I get this error
"microcode: failed to load file amd-ucode/microcode_amd.bin

Right now I try to reinstall by erase all disk again.. (maybe I got lucky this time.. or I could get some error information)

Any suggestion?? Or guide.. Please help me.. Thank you..

[safarin]

After 3rd attempt.. I got lucky.. but after I skipped retrieve installation...