The problem is with your Percent query which is your main form's record source.
However, this is the bulk of your problem:
1. You have 5 tables
NONE of which are related (SERIOUS NORMALIZATION needed).
2. You have
31 queries;
32 forms;
32 reports.
All for just 5 tables

. Lots of redundancy there. At this stage whatever we do wouldn't help your database but would bring more calamity and confusion. Our solutions are designed for relational databases. This is why we've spent a long time trying to give you a solution when in actually fact a solution cannot be reached due to the state of your objects.
Conclusion: From what I've seen you don't understand the basic concepts of a relational database. My advise would be to get yourself with grips with the basics first by picking up some books. Here are some good tutorials that would help:
Access 2003 VBA
Access 2007 VBA
Remember, google is your friend too.
The other option is to leave it for the professionals if you don't have the time. You really don't want to be giving wrong figures to your customers.
If however you decided to do some (thorough) reading, once you've gotten your db sorted, you'll find what we've been trying to relay to you trivial.