I spent all day creating a spreadsheet for someone but every other computer in the whole company we've tried this file on Excel crashes when I try to use it. About the only thing I did differently than I've done many, many times before is I put a bunch of checkbox activex controls on a sheet. And I created a bunch of UDF's (User Defined Functions) to determine what is checked and what is not checked. The Error 424 comes up if they try to execute anything from within the VBA editor. On the sheet where most all the checkboxes are located, they cannot even select a component. If I go to design mode, they can select the item but the properties window yields the sheet, not the activex control. This is very frustrating. Does anyone have any suggestions. If I hit Recalc, Excel stops working!