Are you using madExcept 3 or 4? I'm not sure at which BCB version madExcept 3 ends. Is it possible you installed madExcept 4 on the PC where it works and maybe madExcept 3 on the PC where it doesn't work?
Another possible reason is if BCB has remembered the madExcept packages under its "Disabled Packages" (or was is "DisabledPackages"?) registry key. Please do a registry search for this key and check if any madCollection packages are listed there. If so, simply delete the entries and restart BCB.