Analysis Toolpak appears loaded, but isn't
 

I have a project that requires that the Anaylsis Toolpak add-in be
loaded...it uses some of its functions. Things work fine on my
machine. When I pass the project to others the functions are not
recognized even if they have the toolpak loaded. If it is loaded, it
must be unloaded and reloaded before things will work.

Any ideas why this is? A work-around would be to use an workbook_open
event to:
1) load the toolpak if it isn't already or
2) unload and reload if it is

Thanks,
John