Ran into this problem myself. Clean Scripts doesn't work.
After Closing MediaMonkey:
Delete all references to ScrobblerDJ in Program Files\Mediamonkey\scripts and plugins
Delete Everything under ScrobblerDj in scripts.ini in the above folder
Delete Everything under ScrobblerDJ in MediaMonkey.ini in your C:\Users\[YOU]Appdata\Local\MediaMonkey\
or Application Data\MediaMonkey in XP.
Open MediaMonkey and Clean your scripts just for good measure Tools>Options>Clean Scripts>Clean Now.
Just FYI I also uninstalled Last FM Scrobbler for the heck of it. Then reinstalled it.
Download and get help for different MediaMonkey Addons.