Ubuntu 11.10 installed and ran on my laptop flawlessly for the first time.
But during the next startup, when I select Ubuntu from the dual boot Ubuntu/Windows7 I get an Ubuntu colored background for a moment and then a black screen with an underscore blinking for sometime. After that, the monitor goes blank (backlight switches off) but the laptop keeps running endlessly until I remove the battery.
I used the same disk on my PC and I have no problems there. I tried repairing packages but to no avail. I am using a SONY VAIO VPCCB15FG core i5-2410M, Amd RadeonHD 6630.