Comment 9 for bug 910999

Just a bit more information:
This appears to be broken in the 2.6 kernel somewhere as I have just tried a fresh install (USB boot) of natty (11.04) with kernel 2.6.38-8 and it too is broken, but not quite as broken as the 3.0.0-12 kernel. It takes a long time for the failures to time out, but when it does it leaves the drive accessible (you can see it in partition editor)

I will try the latest mainline kernel on oneiric when I get a chance.