I've just recently downloaded a plugin, Mood Changer by DJMystic.  When I click on the install button, a thing pops up, asking me whether or not I'm sure I want to install; I click yes, and then nothing happens.  No hourglass on the cursor, no lagging, no freezing up, no nothing.

Am I doing something wrong?  I first unzipped the file into a folder that wasn't in the Messenger Plus! 3 folder, but the found the folder: Program Files\Messenger Plus! 3\Plugins, and put it in there.

Tried it and it works for me, check if you have the "Moody.dll" and "mood.zip" files in your Messenger Plus! plugin directory (Program Files\Messenger Plus! 3\Plugins) and restart Messenger.

Hm... I checked, and I don't have either.  I deleted the files that were there and downloaded and unzipped the file again, this time initially into the proper folder, and I still have nothing but "read1st","Moody_Readme","installer" and one that brings me to an internet page and that has an incredibly long name.

And simply clicking on install still does nothing.  Just to test it out, I downloaded the "Stuff" plugin, and it gives me a folder with files in it, a .dll file and an installer that works perfectly fine.  Any ways I might get this to work, or is it just a lost cause?

Close Messenger, unzip the file and run "installer.exe". Click "yes" when it asks you if you want to install it and wait, it should tell you the plugin has been installed. Restart Messenger.