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ok. Remember that downloading an application from an untrusted source (even worse with an unknown source) can harm your phone. It could have been a virus that reads your SMS or steals your addressbook.
My advice is to install only applications from the AppWorld.
For the beta version, you can register the BlackBerry Beta Zone, where you could have installed BBM7 beta and benefit from a special support for that beta version.
The search box on top-right of this page is your true friend, and the public Knowledge Base too: