Sounds like a client that is co-resident in the TSM server system,
using the Shared Memory Communications method, as though the client
is at a very different level than the server, so the server doesn't
understand what the client is saying; else there may be problems in
the shared memory area.  I would start by looking for system changes
which may have been effected, which precipitated the problem
condition, as possibly the TSM client being boosted to a high 5.3
level relative to the 5.2 server.

   Richard Sims