Just take it from the top (I think you might have deleted the wrong thing...): Uninstall LW through the control panel (Add/Remove programs) and make sure you also delete the Prefs as LOTR said (if you can't find them, then tht could be a sign that you had deleted the right thing).
Go to www.limewire.com and download the latest Pro version (since you said you bought Pro...). I strongly recommend that you download the beta Pro instead of the regular version as it has more cool features.

I am still gettting the error message. even after I uninstall and reinstalled lw