There is a very similar bug here: "xhci_hcd: Timeout while waiting for a slot - Issue with USB3 hard disk on 11.04 x86_64" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/775543 (can I link these bugs together somehow?)
There is a very similar bug here: /bugs.launchpad .net/ubuntu/ +source/ linux/+ bug/775543
"xhci_hcd: Timeout while waiting for a slot - Issue with USB3 hard disk on 11.04 x86_64"
https:/
(can I link these bugs together somehow?)