After using it for a good few hours, I launched a shell script in a terminal and got the traces below.
I hope this helps (if not, please let me know how to make it helpful or I'll just stop testing -rc kernels and save myself some time)
[ 4788.218951] Unable to handle kernel NULL pointer dereference at 0000000000000028 RIP:
[ 4788.218959] <ffffffff80247381>{inode_has_perm+81}
[ 4788.218971] PGD 2485f067 PUD 0
[ 4788.218975] Oops: 0000 [1] PREEMPT
[ 4788.218977] CPU 0
[ 4788.218979] Modules linked in: parport_pc lp parport eeprom i2c_sensor i2c_viapro i2c_dev i2c_core rfcomm l2cap bluetooth sunrpc ipt_REJECT ipt_state ip_conntrack iptable_filter ip_tables dm_mod hotkey container tsdev usbhid yenta_socket rsrc_nonstatic uhci_hcd ehci_hcd shpchp via_ircc irda crc_ccitt
[ 4788.218995] Pid: 19002, comm: ssh Tainted: G M 2.6.13-rc5