I have a small Excel application (1MB) with some hidden sheets. I also have an input sheet with a series of combo, list and textboxes. But, for some reason while I am running the application, part of the input sheet gets greyed out. Now, this doesn't happen often and I would say its rare but it does bother me. My input sheet has a 'Calculate' button which goes out to get data from the hidden worksheets and total some fields. And it happens where part of the sheet 'hangs' and parts of columns get grey out. I'm thinking it's because I have a bunch of other applications running and minimized on my task bar. Anyway, is there a way to prevent this from happening?