Hi Phil,
In the main app you should also be cleaning up, closing/disposing the Datasets also then. Assuming they are being updated.
And can you change "i" to Int32 or Int64... Just curious if it's the counter causing the problem in the test app.
BUT.... Forget the test app, it really isn't anything like real life and simply shows there is some kind of limit somewhere and I suspect it's just an internal or external counter.
What is the actual issue you are having and after how many report jobs?
Is is consistent?
Check your \system\temp folder, are there any file being left behind?
Don