[Samba] winbind caching problem

[john knox]

I am running winbind from samba 3.0.10-1 on fedora 3 boxes authenticating to a 
microsoft 2k3 domain controller.  If I do a 'getent passwd' or a 'wbinfo -u', I 
get a nice long list of names and can then log in to the linux machines with a 
windows account.  If I wait a few minutes, I can no longer log in with the same 
account - even though running 'wbinfo -a <username>%<password> returns:

plaintext password authentication succeeded
challenge/response password authentication succeeded

At this point, even if I try a 'chown <fname> <username>', I get:

chown: `<username>': invalid user

Am I right in assuming that the chown command has nothing to do with pam, so the 
problem can't be there?  For any of the above commands, the linux box and the 
windows machine exchange a bunch of packets (which I haven't yet had time to 
look at closely).  The 'password' line in the nsswitch file is just:

passwd:     files winbind

Re-running the user enumeration will re-allow logins and the chown command for 
another few minutes.  I have tried clearing the /var/cache/samba database and 
restarting winbind to no avail.  There is no nscd daemon running.  Anyone have 
any other suggestions?

        john