I also have this problem on Xubuntu 13.04. When I disconnect the connection, there is a kernel panic. If you try to restart the machine without disconnecting, there is also a kernel panic.
There is a workaround. You click on the bluetooth icon and disable the bluetooth. The connection drops without the kernel panic. If you enable the bluetooth connection again, in the NetworkManager you get some unknown or garbled name for your connection. If you logout and login again, the name of the connection is correct again and you can connect without a problem.
I also have this problem on Xubuntu 13.04. When I disconnect the connection, there is a kernel panic. If you try to restart the machine without disconnecting, there is also a kernel panic.
There is a workaround. You click on the bluetooth icon and disable the bluetooth. The connection drops without the kernel panic. If you enable the bluetooth connection again, in the NetworkManager you get some unknown or garbled name for your connection. If you logout and login again, the name of the connection is correct again and you can connect without a problem.