Na netu jsem našel tohle, tak to po defragmentaci vyzkouším..
I'll give you a mix of fixes. Choose what applies to you:(thanks to dannyboy):
At the LiveCD initial boot screen:
o Select F6 for more options
o Add the following option to the beginning of the options list:
break=top
o Press enter to start booting
Ubuntu will start booting, but kick you out to a command prompt; at the prompt type these two commands:
modprobe piix
exit
You will now boot into the LiveCD normally.