Install one, then use it until you are satisfied it is problem-free. Only after that should you consider installing another piece of beta software. If you have several beta programs running simultaneously on your computer, you won't know which one is causing trouble. Finally, provide feedback. Let the developer know what happens.
Most beta software comes with instructions on how to report problems.
I just signed up for high-speed, always on Internet access, and so far it's been great. Also, I can't send or receive a fax from this modem. Doing that occasionally isn't too bad, but having to disconnect and reconnect the lines from my high-speed modem several times a day is a major headache. I thought maybe I could install some kind of telephone line splitter that would let me use both modems at once, but the telephone company says that won't work. My Internet service provider hasn't been much help either.