The VBS is calling a stored procedure... There's some logic in there, and finally an insert, and yes, there is a join to another table.

But as I mentioned, it's working 99% of the time, and the error capture section generates calls to the stored proc that I am able to execute successfully by hand.

The error text suggests to me that the call is not actually getting to the SQL Server -- but then if I had a clue what the error was telling me....