Excel Crashing when copying cells. If I highlight a section of cells with data and do a command C, Excel crashes. Excel 2008 was continually crashing for any operation using Mac OSX 10.6. whatever the last update was. Thinking that the crashing may be caused by an operating system to older software issue, I upgraded to OS 10.7.3 (lion) and purchased Excel 2011. Everything was working fine on large spreadsheets until this evening, when I tried to copy paste on a small worksheet and then every time I hit Command C, Excel would crash. Would appreciate any assistance, as this is going to adversely affect completing a project. Additional fact, the worksheet that the data was copied from was an older Excel file (circa 1996 +/-) , brought forward to Excel 2008 and then into Excel 2011.