I've never heard of this problem before, okay try the following:
Download the latest Messenger Plus! from
http://shoutbox.menthix.net/download.php
Exit MSN Messenger
Go to Control Panel > Add Remove Programs > Messenger Plus! and completely remove it (also go to C:/Program Files/ and delete the "messenger plus! 3" folder.)
Go to Control Panel > Add Remove Programs > MSN Messenger > Change > Repair
Then reboot your computer, and try reinstalling Messenger Plus!, if it has the same error, then do the following:
Download
StuffPlug, install that, restart MSN Messenger, in the configuration panel, check the option that says "Remove 5 Custom Emoticons Limit" (or something along those lines).
