I'm not sure I'm helping, but can you answer a couple of questions?
Do you have windows explorer set to show extensions? If no, turn this on:
Windows start button|Settings|control panel|Folder options|View Tab (in WinXP).
Make sure "hide extensions for known file types" is not checked.
Now when you open a workbook named test.xls, what do you see in excel's title
bar? If you're seeing test1 (with no extension, then excel is opening that
text.xls as a template.
In my minor testing, this wasn't a function of how the workbook was saved, it
was a function of how windows/excel opened the file.
Open windows explorer, traverse to the folder that holds that test.xls workbook.
Rightclick on that workbook.
You'll see windows default action in bold (for .xls files, it should be Open).
For real template (.xlt), you should see New in bold letters.
If this is not what you're seeing, you could try to change the settings manually
(usually a pain). Or maybe simply reregistering excel would fix it.
Close excel
windows start button|Run
excel /unregserver
then
windows start button|Run
excel /regserver
The /unregserver & /regserver stuff resets the windows registry to excel's
factory defaults.
----
If you're clicking on test.xls and seeing test1.xls open, then that wasn't the
problem (although the /unregserver & /regserver can't hurt to try.
The only time I've seen a character added to the file name like this is when I'd
open an excel attachment in an email. Some email programs (Netscape
Communicator is the one I remember) will notice that there's a file using that
attachment's name (in Netscape's work folder) and the email program will add a
digit to make the name unique.
But I've never seen that happen just by doubleclicking on a file in windows
explorer.
I'd try the /unregserver & /regserver stuff just to be able to say I tried it.
It may help the next person's suggestion.