Any time I tried to use z4root on my Cliq 2, it would completely freeze the phone. I tried a number of different trouble shooting steps (battery pull, restart after installing, running it in airplane mode with and without wifi, gps, and bluetooth enabled), and every time, same result.
I found another method that's intended for the Droid, Droid 2, and Droid X, that uses the terminal emulator app, and it pretty much did the same thing.
Finally, I decided to try Gingerbreak for no real reason other than I hadn't tried it yet and was out of ideas. Five minutes later, I had a rooted phone.