Developing on 2007. Running on 2003. Subform Issues.

[sgrace]

I have Access 2007. Developed a system for client base that runs some 2003, so created the database in 2003 format. The system mostly works fine for the 2003 folks but some issues with subforms. The filtering doesn't work and a subform will lock up after a user uses nav bar to scroll right.

Anyone heard of this? Suggestions for addressing?