Working with Excel when I received message it had experienced problem and would shut down. Opened file again with no problem. When I tried to enter data, program shut down again. Tried with various files with same result. Could enter data in a new file, but when I reopen it, it also shuts down. Can copy data in file, but when I try to enter data in new file, Excel shuts down again. Can I reinstall Excel and eliminate problem, or is each data file corrupted? Thanks!