[Samba] alloc_sub_basic: NULL source string!

[Jeff Umbach]

Starting three days ago I have found over 4,000 of these error messages in
my messages log.

Mar  5 15:49:48 fs3 smbd[13785]:   alloc_sub_basic: NULL source string!
This should not happen

Nothing has been changed on the samba config in over a week and that change
was about the spin lock time setting.  The server is RedHat ES 3 running
Samba 3.0.2.  The client machines are a mix of Win98 and WinXP Pro on a
domain with Samba as the PDC.

The only effect I have seen on client machines is that one WinXP Pro box
once took several minutes to log in and load it's roaming profile from the
server.