The most common causes for this is Smileycentral (
uninstall instructions here) and previous use of the handwriting plugin. You don't need the full plugin anymore when using MSNM 7. In your case i expect it to be the handwriting plugin. To solve that exit MSNM then go into the pluginsfolder (C:\Program Files\MessengerPlus! 3\Plugins, there can be several MessengerPlus! folders..check them all) and delete handwriting.dll. Now restart MSNM and all should be ok.
If it isn't that, can you take a screenshot of that optionwindow? Also tell wich plugins you use.
Edit: you're welcome
/ 
