Problem #2 - Plus! not integrating, even when I don't have Smiley Central!
Maybe you've previously installed Smiley Central and the dll file is still sitting in Messenger's folder?
In Control Panel > Programs, select Messenger Plus! Live > Uninstall/Change >
Repair Messenger, then try.
If that didn't work, uninstall Windows Live Messenger and Messenger Plus! Live. Restart your computer. Download both and try again.
Problem #5 - I still can't install Plus! after trying everything!
Are you using any security programs, such as: anti-virus, firewall or internet security?
This could be preventing Plus! from writing to the registry.
You can try manually allowing WLM and Plus!, otherwise you may need to disable or uninstall it.