>TSM Server Diagnostic: ANR9999D: Error reading from disk
>D:\TSMDATA\SERVER1\TSMDB1.DSM. Reason: 33

...

>Does anyone know what reason code 33 means, or what is going wrong ?

Refer to your Microsoft error codes reference for such numbers.
From my reference, it says:

 33                 The process cannot access the file    ERROR_LOCK_VIOLATION
                    because another process has locked a
                    portion of the file.

>The error occurs when clients are doing an incremental backup.

Might the NT client you are running be backing up the D: drive where
the database itself resides?  Or some other conflicting process is
going at the database?  Just possibilities.  I don't see any relevant
BUF011 reports in the APARs repository.

    Richard Sims, BU