There's not really much for us to go on here, but...
to start at the very basic...
when you were adding code  to the web toolbar, where did you store it?
What is the name of the file?
if you're hiding file  extensions, looking at the file in an Explorer
window only shows the filename, not the extension.
One place toolbars are stored is in .xlt files.
The icon in explorer LOOKS like an excel  icon, because .xlt files are
for excel, but the act like add-ins and are not displayed.
(kind-of like your personal.xls file, but not quite. It is called up
each time you enter excel, but it doesn't get displayed either)

just for grins, try renaming the file to newfile.xls and see if you can
call it up...

again... this may not be the problem, but it IS a techniqe for creating
and distributing toolbars.