Thanks for all of the feedback. I think the with recompile option is probably the best choice looking back. The hints thing didn't work because you really didn't know the size of the tables. Just because it was a large date range didn't mean it was a larger data set. I wanted and trusted the server to choose the right plan, which it did when it was recompiled. I also want to clear up that I wasn't blaming .Net. I was just stating what we saw, but the points that have been raised are valid and should be considered when trouble shooting. For me, the big thing here was discovering how and why the engine chose the type of join it did, and what that join was best at. The difference between query analyzer and the .Net application just help to shed some light on it. I am pleased with all of the discussion that has taken place and all of the wonderful ideas that have come from the discussion. Thanks for keeping it positive and adding value to the discussion.

-mike