duh
Try the usual fix(es) for this problem.
Tools>Options>General uncheck "Ignore other Applications"
Exit Excel and try again
If this doesn't work try to re-register Excel
Close Excel first and
On the Windows Taskbar
1) Start>Run "excel.exe /unregserver"(no quotes)>OK.
2) Start>Run "excel.exe /regserver"(no quotes)>OK.
See the space between exe and /regserver
You might have to designate a full path to excel.exe.
In that case Start>Run "C:\yourpath\excel.exe /regserver"(no quotes)>OK.
Gord Dibben Excel MVP
>How do you prevent an error message from showing up when an Excel 97 file is
>opened. The error message states: A document with the name (file name.xls) is
>already open. You cannot open two documents with the same name even if the
>documents are in different folders.