That's really strange. Which RailClone Pro version are you using?
I would suggest you to delete all keys under
HKEY_CURRENT_USER\SOFTWARE\Itoo Software\RailClone Pro
HKEY_LOCAL_MACHINE\SOFTWARE\Itoo Software\RailClone Pro
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Itoo Software\RailClone Pro
and reinstall the plug-in. Thanks in advance for any further comments on this issue you can share about it with us / our user community (in case some user(s) will run into similar troubles).