Comment 9 for bug 404596

I got the same problem too but I think the cause is an Ubuntu specific patch or something similar.
For me 2.6.30.10-generic from Karmic does not work but this works:

http://blog.robertalks.com/index.php/2009/09/10/kernel-2-6-31-final-released-for-debianubuntu-final/

The source and the compile options are published.
You should check the difference between the two kernels and You will find the bug.