Complete reinstall of Cubase 5

Hi there!

I want to make a complete reinstall of Cubase 5 and all my 3:rd part plugins on my Mac. (OSX Snow leopard)
Is there any way to remove all of the files including all plugins and software synths?
Why i want to do this is because one of my 3:rd part plugins (ReFx Nexus) stopped working when i upgraded my computer to OSX Lion for some reason.
And when i downgraded back to snow leopard again it was still broken. Even when i tried to reinstall Cubase and the plugin. I tried to use a Mac cleaning program to remove all files anv preferences and reinstall them but it did not work. Nexus still didnĀ“t work correctly.

Does anyone have some idea of how i can do this?