Do you have another script with an "on Input" event in it? If so u need to add the following line as the first line to be executed in that event: if (!$inpaste && $mouse.key == 4) { halt }

And some information I need to know:
What mIRC version are you using? You will need v. 6.2 or later
What OS & version are you using? You will need Win2000 or later
What MS Word version are you using? You will need MS Word 2003 or later
What kind of scripts do you have loaded? There might be a conflict between my script and those
Do you have your mIRC client set to OnTop? This will cause the box to appear behind mIRC.