Platform and os is the server.
Client is running MSDOS 6.22 with lanman 2.2
Client works on samba 3.0.23, fails when I tried to upgrade to 3.2.3.

Test smb.conf  

> # Samba config file created using SWAT
> # from UNKNOWN ()
> # Date: 2010/02/02 13:20:51
>
> [global]
>       workgroup = ATRIUM-DW
>       guest account = bbijimhur
>       lanman auth = Yes
>       ldap ssl = no
>
> [bestbilt]
>       comment = working production data
>       path = /atrium/bestbilt
>       username = bbijimhur
>       valid users = @users
>       force group = users
>       read only = No
>       guest ok = Yes
>
> [dosbbilt]
>       comment = win94 for dos workstations
>       path = /atrium/bestbilt
>       read only = No
>       guest ok = Yes
 ******************************************

I can log in on the dos station and map the share.
When I attempt to run an executable I get the following message on the dos station.

> u:\win94\>  Tracking
>
> NET805: NETWORK DEVICE NO LONGER EXISTS READING DRIVE U
>
> Abort, Retry, Fail?
>
> f
>
> Access denied.

I sent Gunter Kukkukk a section of the log.smbd at log level 10 for the time period of interest.  About 3000 lines.

When I attemped to post it here, bugzilla said "too big"
I will be more than happy to send log files or anything else on request

Jim