Excel 2007 doesn't open files selected using Explorer or Recent Do
 

I am trying Office 2007. If I open Excel, then use Office Button/Open/ then
select a file, or Office Button/Recent Files and select a file, they open
fine. But if I use Windows Explorer to navigate to a file, then double-click
it; or if I use the Start Menu/My Recent Documents to select a file, Excel
opens, but the file does not. If I then try to open any other file, the
requested file does open. But if, instead, I try to exit Excel, I get an
error message it can't find the file. Can anyone help diagnose this problem?