Excel 2007 : Bug?:Autofill formulas in large databases

This problem is driving me batty. I have a file that contains 12 sub-sheets and most sheets measure 300 cells down, 850 right. I've designed this as a sort of "plug and play" for research databases so all a person has to do is put the file in the folder and Excel will go through all the processes.

Almost every cell in this file is a formula. Anything from simple reference (=Data!A2) all the way to 25 argument formulas.

Here's the problem: When a larger database is plugged in I need to expand the formulas down to accomodate it (current study has 300 participants, so it goes 300 down). Usually, this would work easily with autofill by highlighting the whole row and dragging down. This is where a maddening bug comes in...

Certain columns do not want to be autofilled with others. If I have that cell and a nearby cell highlighted and try to drag down it gives me a "Selection is too large" error. Of the 850 columns, about 40 of them refuse to cooperate with others during autofill. I can only autofill that column individually then autofill the cooperative ones together. There is NO difference that I can see between the cooperative and non-cooperative columns. One of the trouble columns is even a simple reference (=A3)!!!!.

So... do any of you know what bug is stopping me from autofilling the whole sheet down a few notches.. and if not, is there a way for me to format my database to automatically bump down the formulas when a larger plug-in data set is used (I/e a study with 800 persons).

Thanks, please let me know if I can clarify my problem better. I'd love to post my database so you can see for yourself, but I can't share the data with outside sources =(.

The issue is partially solved. By making every sheet a table I can have everything expand by dragging down a single autofill cell and it automatically fills for all tables and checks the formulas.

I still don't understand why I can't manually do the same thing (drag across and autofill down (x) cells).