[Samba] Sudden domain login problems from XP-pro sp2 clients, Please help!

[henry]

Update:

I had to remove every PC on the network from the domain, delete the 
machine account from the pdb backened, and then rejoin the computer to 
the domain. I am starting to realize that the problem stems from a 
corrupted pdb backend, as now, some accounts (samba not unix) have 
dissapeared. Some of the accounts I can just re-add via smbpasswd -a, 
set their password, and then they can login. But other accounts will not 
allow me to login after I do this. There are a whole bunch of these 
corrupted accounts. Running pdbedit -u username -v, and comparing to 
working accounts, I can't tell any difference. I AM able to connect with 
the bad usernames to regular shares, I just can't login to the domain.

What do I do???