Personally I don't use the plugin. I've had stability issues.
Rather, I added Melodyne (and others like iZotope RX2) to my Tools menu.
http://www.cakewalk.com/Support/kb/reader.aspx/2007013099 Now when I want to tune something I will create a new layer and copy the vocal there, mute the first layer, select the second, and go to Tools and select my editor (in this case Melodyne.) Then I edit in the full Melodyne Editor, Save, and it will be imported back into Sonar automatically.
I find this much more usable than using the plugin anyway, and it's more stable.
BTW I'm using 1.3.0 (64-bit.)
Peace,
Tunes