I also have this problem, with a Dell Studio XPS 16 (1640), but neither the 2.6.34-rc4-lucid or the 2.6.32-20.29 kernels work for me. I had already submitted the bug(https://bugs.launchpad.net/ubuntu/+source/linux/+bug/552876), and later, marked as a duplicate of this, but now I think that may be a different problem.
I also have this problem, with a Dell Studio XPS 16 (1640), but neither the 2.6.34-rc4-lucid or the 2.6.32-20.29 kernels work for me. I had already submitted the bug(https:/ /bugs.launchpad .net/ubuntu/ +source/ linux/+ bug/552876), and later, marked as a duplicate of this, but now I think that may be a different problem.