When you use CMD+W or the Close command on the File menu you are closing the
workbook. Since you're closing the workbook, you're also closing all the
windows associated with that workbook. If you want to just close one of the
windows and not the workbook, click the red X button in the upper left
corner of the title bar of the window. There isn't a keyboard shortcut for
closing just one window of a workbook.
Please post again if that doesn't solve the problem.
Todd Aton
Macintosh Business Unit
Microsoft Corporation
Microsoft makes no warranties, express, implied or statutory, as to the
information in this post.