Also check dmesg, PolicyKit is SEGFAULTing. Mine shows (after trying to unlock):
[ 134.212257] polkitd[972]: segfault at 0 ip b78b93da sp bfff3530 error 4 in libpolkit-backend-1.so.0.0.0[b78ae000+15000] -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]

