excel opens blank window - why?

[cougarfan1]

When I open an existing workbook, another window opens alongside that is blank Excel. Why? This just started happening and requires closing the blank window separately. I can close it either before or after finishing work with the workbook I opened, but why is it there at all? It's annoying and doesn't happen with all workbooks, but I can't see what makes the difference if there is one, and why it's happening in the first place?

[nahidking]

same problem is with me...