Hi Kelly,

When you use a commandbutton to trigger a macro, the button itself usually takes focus. This may or may not be the issue, as we don't see any of your code or a sample workbook.

Also, whenever you are working with multiple worksheets and workbooks, ALWAYS ALWAYS ALWAYS preface any range argument with the fully qualified parent object reference.

For example, instead of Cells.Select, try Sheets("Sheet1").Range("A1:G20").Select. If you have to reference Sheets("Sheet1") many times, use a With/EndWith clause.
With Sheets("Sheet1")
    .Range("A1:A10").Copy Sheets("Sheet2").Range("A1")
    .Range("B1:B10").Copy Sheets("Sheet3").Range("B1")
End With
Also, it is rarely necessary to select any cells to actually perform a task. If you do a lot of select and activate statements, it will tend to slow down a macro (especially within loops).