As of today (8/5/12), I tried both suggestions, and it does not seem to work. I have even tried re-starting my computer, and it doesn't seem to work.
I originally asked a question about how to un-install Rhythmbox... In that question, I also asked how do I turn off updates for Rhythmbox... That never got answered.
When I updated from Ubuntu 11.10 to Ubuntu 12.04, you guy's replaced Banshee with Rhythmbox... Well, I like Banshee better, so when I uninstalled it, next time Update Manager opens, it gives me a bunch of "updates" for Rhythmbox... which includes re-installing it... how do I stop this?