I took a look at the script (I even wonder how it even got in the script database!) and I'll try to help you out.
- Open your Plus! Live preferences by clicking the Plus! icon in the contact list and select "Preferences", or by sending the command "/prefs" in a conversation window (that is: type and press "Send").
- Navigate through the tabs to General > Scripts.
- Look for "Joker" in the list and untick it (click on the checkbox next to it so that it's not ticked anymore).
- Click "Apply".
- Try to remove the script by looking it up again in the list and click "Remove..."
- You should now be able to change your personal message. If Plus! tells you it couldn't remove the script, continue with the following steps. If it didn't, stop here.
- Browse (in a Windows Explorer window) to "C:\Program Files\Messenger Plus! Live\Scripts". Note that this is the default path, if you're on a 64-bit system, you'll need to look in "Program Files (x86)" for example. Just make sure you're in Messenger Plus! Live's scripts directory!
- Make sure Messenger is shut down, by right-clicking the system tray icon (next to the clock) and choose "Exit".
- Try to delete the folder "Joker".
- Start Messenger again, and see if it works now.
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