it's a common problem with 0022 and ubuntu
I just put together/fixed a HP g60-535DX laptop. I download the Ubuntu 11.04 64bit iso image, install it, upgrade it to the newest kernel (2.6.38-10-generic) and applications. Installed arduino via apt-get and it works great. I would suggest upgrading the kernel to version 2.6.38-10. You can check the kernel version by executing an "uname -r". note: I have only tested the on the Diecimila. I have an old old laptop with the ubuntu 11.04 32bit that I will test today. Works on 32bit version, same kernel version.