samba - Nov 2003 - win98 users authenticating with Samba PDC, but accessing shares as guest

I recently migrated an NT4 PDC to Samba 2.2.2 on Debian Woody.  I used the
pwdump2 utility to dump the NT SAM so that it was suitable for Samba. 
Everything went pretty smoothly.

The issue seems to be now that although users on Windows 98 are
successfully authenticating against the Samba PDC (i.e. if I use a known
invalid account/password pair, I get an authentication error as I would
expect) all but one or two users seem to be getting bound to the
guest (nobody/nogroup) user rather than who they authenticated to the PDC
as:

# smbstatus

Samba version 2.2.3a-12.3 for Debian
Service      uid      gid      pid     machine
----------------------------------------------
Share1$      nobody   nogroup  13869   mach1    (192.168.0.11) Thu Nov 27
08:47:33 2003
User1        User1    users    13844   mach4    (192.168.0.100) Thu Nov 27
08:10:38 2003
Software     User2    users    13871   mach5    (192.168.0.21) Thu Nov 27
08:50:11 2003
Mail$        nobody   nogroup  13788   mach2    (192.168.0.19) Thu Nov 27
07:38:49 2003
Share1$      nobody   nogroup  13845   mach3     (192.168.0.13) Thu Nov 27
08:11:43 2003
Drivers$     User2    users    12544   test     (192.168.0.17) Wed Nov 26
08:54:41 2003
Drivers$     nobody   nogroup  13869   mach1    (192.168.0.11) Thu Nov 27
08:47:34 2003
Apps$        nobody   nogroup  13845   mach3     (192.168.0.13) Thu Nov 27
08:11:43 2003
Word$        nobody   nogroup  13788   mach2    (192.168.0.19) Thu Nov 27
07:38:49 2003
Drivers$     nobody   nogroup  13845   mach3     (192.168.0.13) Thu Nov 27
08:11:43 2003
Apps$        User2    users    12544   test     (192.168.0.17) Wed Nov 26
08:54:41 2003
Apps$        nobody   nogroup  13869   mach1    (192.168.0.11) Thu Nov 27
08:47:33 2003
Word$        User1    users    13844   mach4    (192.168.0.100) Thu Nov 27
08:35:08 2003
Share1$      User2    users    13871   mach5    (192.168.0.21) Thu Nov 27
08:50:11 2003
share2       nobody   nogroup  13845   mach3     (192.168.0.13) Thu Nov 27
08:11:42 2003
printer      nobody   nogroup  13869   mach1    (192.168.0.11) Thu Nov 27
08:47:34 2003
Public$      User2    users    12544   test     (192.168.0.17) Wed Nov 26
08:54:41 2003
printer      nobody   nogroup  13845   mach3     (192.168.0.13) Thu Nov 27
08:11:43 2003
Public$      nobody   nogroup  13869   mach1    (192.168.0.11) Thu Nov 27
08:47:33 2003
WP$          nobody   nogroup  13788   mach2    (192.168.0.19) Thu Nov 27
07:38:49 2003
Public$      nobody   nogroup  13845   mach3     (192.168.0.13) Thu Nov 27
08:11:43 2003

User1 is on Windows XP, but the rest are on Windows 98.  As you can see,
User2 successfully "binds" to her Linux uid/gid, but the rest are all
bound to the guest account uid/gid.

Any ideas why this would be?

Thanx,
b.