If the problem is that you're having trouble doing other things on the computer at the same time, you might want to try reducing Excel's CPU priority. So if you run something else, Excel will be forced to stop and wait since your program has a higher priority. It will take longer to finish, but you should be able to do other things at the same time.
Instructions for Windows 7:
- Open the Task Manager (Ctrl+Alt+Del)
- Open the Processes tab. Right-click on excel.exe and go to Set Priority.
- Choose a new priority. Most processes run at Normal, so you can use either Below Normal or Low.
This is temporary, so you'll have to do it again if you quit Excel.