Got a laptop that I suspect has a corrupt Master boot record from a virus (previously running Windows 7). I'm trying to boot ubuntu from a USB stick in order to back up the files that are on the hard-drive.

I've downloaded ubuntu 12.10 onto a usb and get the screen with the stick/man. I initially had problems with it booting to a black screen, after searching I found I need to add the nomodeset option from the F6 menu.

After choosing this option I get the Ubuntu load screen (with the dots underneath) but it won't boot to the Ubuntu main screen - it stops at the GRUB screen with the prompt.

Then, after about 1 minute some information appears and the screen goes black again. I've videod the screen to get the message and just before the screen goes off the message is:

[199 039566] init. udev-fallback-graphics main process [4170] terminated with status 1

If anyone can help me with:

A - why I dont get the Ubuntu main menus and
B - why the screen suddenly goes off

I would be most grateful.

Thanks in advance.