[binc] BINC quirks on Mac OS X

I recently transitioned my mail server from Linux to OS X, and as part 
of that moved over my Postfix/BincIMAP/Thunderbird setup.  Everything 
went quite smoothly, but now I'm seeing some glitches:

In Thunderbird, if I navigate to a folder that contains many messages 
which the server doesn't know about (for example, my Spam folder, which 
currently has 1669 messages), some subset of the messages will appear 
(with header downloads), say 800.  If I navigate to another folder and 
back, more messages will appear.  Only after I've navigated back and 
forth a few times will all of the messages appear.

A few times while I've been looking at a large folder, all of the sudden 
most of the messages will disappear.  For example I was reading through 
the folder with 840 binc mailing list emails, and suddenly most of the 
messages disappeared and the message count went down to ~150.  I 
navigated away from the folder and back, and the count went up to ~500. 
  Another away and back, and it was back up to 840.

If I have a folder with a lot of unread messages (say 500), and I Select 
All and Mark as Read, it appears that all of the messages are read, but 
then if I navigate away from and back to the folder, the unread count 
goes up to only slightly lower than it was (say 480).

Has anyone seen these kinds of problems?  I'm wondering if there's some 
filesystem issue with HFS+ where binc operations are terminating 
prematurely...

I'm running Binc IMAP 1.2.10final and Thunderbird 1.0.2 on OS X 10.3.8. 
  And before somebody points out that I should upgrade to 1.2.12 and do 
a protocol dump, I just want to see if this is a known problem first. 
I'll do more investigation if not...

Seth