When a Z-Read is done the database synchronises fine. The following day it gives a run time error when a Z-Read is done '-2147217900 (80040e14) [DBNETLIB][ConnectionOpen(Connect()).}SQL Server does not exist or access is denied.' POS then restarts and the next time Z Read is done it Synchronises fine.
So problem occurrs next time after a successful Z read then synchronisation. Then is resolved after POS restarts.
This is a store that is running 1.3.1005 - The database is on a Local network PC and on 3 Tills pointing to the database the problem is occurring.