TAC indicated that the workaround is to disable all signatures for the "MSRPC" and "SMB Advanced" engines. I haven't tried this yet.

In my experience, it has proved best to delay production deployment of a new major version of network device software until the third published minor release (whether it be Cisco or another vendor.) Thus, I am running 4.3.6 for the time being.

MARS 6.0 release was delayed until late September last I heard.