Shoutbox

- Start > Control Panel > Add/Remove Programs > Messenger Plus! 3 > Change\Remove > Follow uninstaller
- Reboot your computer
- Download and install Messenger Plus again, has the problem gone?

If that does not fix it try this;
Main Messenger Window > Plus > Preferences > General Options > Miscellaneous > Make sure at the bottom under "Messenger Plus Automatic Recovery Options" you see a box with an arrow next to it, click on the arrow and make sure "alternate mode" is selected. Then click on OK.
However Alternate mode should be active after you have applied the recovery anyway. If you do change to alternative mode, reboot your computer so it can take effect.

Does disabling any plugins (Main Messenger Window > Plugins) fix the problem? Try unchecking the box next to "Allow Messenger Plus to load plugins in my account". Does the problem still happen?