freebsd stable - Apr 2010 - Problems with gmirror locking up on recent 8.0-STABLE/i386

I have a machine used as a firewall which boots from a pair of
drives mirrored using gmirror. This has been in situ for a long
time, and was upgraded to 8.0 a while ago.  Just before the weekend
I upgraded the kernel to the latest STABLE to get the new em code.
After doing this I observed that at seemingly random points the disc
system would 'lockup' by which I mean that all networking continued
fine, but if you tried to do anything which would read or write the
disc then that would pause forever. Only fixed by reboot, and on
reboot the array was degraded, and always resynced the same drive.

"dying drive" I thought to myself - seemed a resonable conclusion.

Except today I took another machine (completelt different hardware BTW)
and build a new system with different drives, but the same gmirrored
configuration - and an hour after I had installed it, it locked up
in exactly the same way. Just after I upgraded it to match the version
of the kernel running onthe original one in fact.

So now I am wondering if there is some unfortunate problem which has
crept into gmirror in the last few weeks. Has anyone else seen anything
like this ?

-pete.

Just following up my own email, but soemthing is definitely up
with gmirror, as it has got to 100% complete on the
resync, but stays in degraded mode... i.e.

$ gmirror status
        Name    Status  Components
mirror/pair0  DEGRADED  da0s1
                        da1s1 (100%)


this, obviously, shouldn't happen should it ? I am thinking maybe I
should resync my code and rebuild my kernel.

-pete.