I like that answer, Occam's razor and all that...

Well, speaking as someone who makes his living doing Accpac customizations, I strongly suspect a bug in that modded screen.  Just because it doesn't touch that field doesn't mean it can't screw up occassionally.  One tricky part of OE screen mods is how to work with the OnRecordChanging and OnRecordChanged ...

You should be on update 2, but I don't think that's the source of the problem.  Do you have any custom modules or add-ons to OE?

My first suspicion is user error.    But in any case, what version and service pack of OE, and which database?

Make sure you create your DSN's with the 32-bit version in C:\Windows\SYSWOW64\ODBCAD32.EXE.  Otherwise, your setup sounds fine.

Today I'm upgrading one of our clients from version 5.4 to 5.5, and as part of that upgrade, all batches in AR and AP have to be deleted or posted. I thought they were ready before I arrived.  But when I got to the A/P Payment Batch screen, there were over 75 open payment batches, dating back to March of 2006. One was for several hundred ...

Instead of a Record Selection formula, try a Group Selection formula.

Yes, nothing will happen because the selection critieria is passed in by the UI, just like the comment says.

Copy the folders.

If it works on a copy of the database, then a Dbdump/Dbload should fix it.