It looks like you're a) connecting to the database, b) sleeping for 40 minutes, and then c) trying to run a query, which fails under some circumstances.

It feels like you're trying to reproduce something that you haven't told us about. Why would you connect to a database and then sleep for 40 minutes?

How about a) connecting, then b) loop 40 times, doing a ping on the database handle after sleeping for a minute, and finally c) running the query. I'm guessing that would have a better chance of working, but have no idea what's behind the curtain.