SMB Signing currently does not account for the mutiple outstanding replies that may be present, and will drop a signed connection during file transfer. A list of outstanding packets, and their sequence number should be created, so inbound packets can be matched. smbtorture RW* tests show this well.
A fix has been applied to Samba 3.0 CVS.
originally reported against 3.0alpha23. Bugzilla spring cleaning.
sorry for the same, cleaning up the database to prevent unecessary reopens of bugs.