Comment 7 for bug 465350

I have the same problem.
Also for me the machine does not boot with the default boot options,
but does boot if I remove "splash" from the kernel command line
or if I set the resolution to 1024x768 in startUp-manager.

Fresh install of 64 bit Karmic
GNU GRUB version 1.97~Beta 4 (i.e. grub 2)
kernel: 2.6.31-20-generic #58-Ubuntu SMP Fri Mar 12 04:38:19 UTC 2010 x86_64 GNU/Linux

Hardware:
ASUS P5B mainboard, Intel Core 2 6300
VGA compatible controller: ATI Technologies Inc RV370 5B60 [Radeon X300 (PCIE)]
The screen has the native resolution 1280x1024.

On a second, identical machine a similar installation boots fine with the default options.
For what its worth, this second machine is connected to a different model of monitor (with the same native resolution).