RE: Using GP 2013 R2 utility Customer Combiner and Modifier to combine two customers to one
Richard -
Before you point this out, I know you are on Dynamics GP and NOT NAV; however, this KB article seems like it has the answer to your problem;
support.microsoft.com/.../981995
This problem occurs on a computer that is running Microsoft SQL Server 2008 and that has the Microsoft Dynamics NAV environment installed. Additionally, this issue occurs only if Microsoft SQL Server Replication is enabled on one of the Microsoft Dynamics NAV tables.
If you have Replication enabled, this is likely the problem you're seeing. I know from past experience using PSTL for clients with custom triggers on tables SQL issues can effect PSTL.