Strange issue with Samba on 8.0rc1

I'm having a strange issue with samba-3.3.8.  When I open a file from a 
Vista machine, it's corrupted.  When it's an uncompressed image, I get 
sections where 3308 bytes of pixels are black.  They're not evenly 
distributed, and I'd guess they fill between 10% and 20% of the image.  
If I open the file from an XP machine (in VMware on the same computer), 
this doesn't happen.  It's not the disk; it's ZFS, and the lines aren't 
consistent.  Opening the file from a samba on a different FreeBSD box 
with the data accessed via NFS works (again, not the disk).  The problem 
also happens if I access a file on a non-ZFS disk.

Trying to see if it's a a 8.0 issue, I did a fresh installation in 
VMware (aside: the kernel in the installer crashes with the LSI Logic 
controller VMware emulates), installed samba 3.3 from packages, mounted 
the files via nfs, and it works from Vista.

A 100MB file transfer with netcat between buggy FreeBSD and Vista worked.

I grabbed a fresh ports tree, cleaned it, then did portupgrade -P -R -f 
net/samba33.  Didn't work.  I tried again, but entirely from packages, 
and also removed and reinstalled most of the dependencies, but no luck.  
That time, I even started a fresh smb.conf and deleted /var/db/samba.

My /var was corrupted at one point, so any db there might not have been 
reliable (hence -R on portupgrade).

Ideas?