The following line of code appears to be superfluous:

#my $Excel = Win32::OLE->new('Excel.Application', 'Quit');  # use the 
+Excel application if it's open, otherwise open new
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why not delete it...

Also, try using the following code which I grabbed from the ActivePerl User Guide to check to see if Excel is already running(obviously replacing with your filename variables):

    # use existing instance if Excel is already running
        eval {$ex = Win32::OLE->GetActiveObject('Excel.Application')};
        die "Excel not installed" if $@;
        unless (defined $ex) {
            $ex = Win32::OLE->new('Excel.Application', sub {$_[0]->Qui
+t;})
                    or die "Oops, cannot start Excel";
        }
[download]

Scott