Maybe has a little bit more experience with this. I have a file that is rather large, it does have a lot of formulas many many tabs. I have a process set up where everytime I save the file, because this is a highly sensitive file, I have excel create a backup. It never fails, every month something happens to the file where I click on it and it wont even let me open it. It crashes immediately. I am so frustrated because I have no idea what is causing it and why its crashing. When I repair the file, it will open but all the columns all the formatting is messed up so I dont want to take that copy because it would take me forever to rework it.

Is there a way for me to diagnose this somehow to see what is specifically causing this and maybe I can remove it from my file....

thanks for your help people.