I have a netbook with Windows XP and Ubuntu installed (same drive).
A week ago, I tried to update Ubuntu.
But when the screen saver was activated, the netbook freezed.
I tried everything to shut it down but nothing worked.
Finally I removed the battery. This worked.

Now when I try to boot Ubuntu, it will stop and crash.
The only way I found is to type startx (I think).

Then I tried to update Ubuntu again, but now it says that the upgrade file is corrupted.

Is there any way to repair it?
Can it be done with the Ubuntu CD, Boot Repair or System Rescue DC?

Open a terminal and run "sudo apt-get update" to resync the update file with the repository. When that is complete run "sudo apt-get upgrade".