Named range deletion

I have been developing a very robust model using Excel 07. This model is nearly entirely automated using vba, activeX buttons, and the use of literally hundreds of named ranges throughout the book. I seem to keep experiencing the same problem though. It seems that at random points in the use of the model, a named range disappears from the book all together. Then, when the vba attempts to use that named range, a run-time error is generated.

Has anybody else experienced the spontaneous deletion of their named ranges? If so, have you found a solution to this recurring problem?

Much thanks for the help ahead of time.