If you open the file via doubleclicking in windows explorer:

You can change this setting (xl2003 menus):
Tools|Options|General tab|Ignore other applications (check it)

Be aware that one side effect of having this setting checked is sometimes you
can't open a file by double clicking on it in explorer. (toggle it back and
that should be fixed.)

This shows up for workbooks that have spaces in their name or path:
c:\my documents\excel\testworkbook.xls
or
c:\test of workbook2.xls

Cannot find C:\my, then more "Cannot find ..." messages.

It's more trouble than it's worth (for me, anyway). If I want separate
instances, I'll just start a second instance and use File|Open.

I like a single instance so that I can easily copy between workbooks.

ed godlewski wrote:

I am unable to open multiple workbooks in multiple instances of excel - like
opening multiple word documents in multiple instances of word - is there some
setting or workaround that can resolve this? Working on multiple workbooks in
the same window/instance is very slow, confusing and should be un-necessary

--

Dave Peterson