Getting XP to release named pipes

We have a situation with XP Pro running as a small file/print server, when a shared printer is setup on a client to use the share the connection will not release until you either remove the share or log off. When logging back on or recreating the share the connection is re-establised. This is fine until all the concurrent connections are used up, it seems that the printer shares using the pipes/spoolss does not follow the usual disconnect time out as normal shares. Can anyone shed any light on this please?