CV axle clunking?

I have aclunking sound in the front end whenever I go over bumbs at very low speed. It doesn't do it at higher speeds or when I turn the wheel. The Midas guy looked at it and said he couldn't find anything wrong. Anothey mechanic looked at it and said the CV axle was clunking. If I grab the rubber boot and shake the wheel cylinder, it moves a little and I can hear a clunk. Is this dangerous to drive? Do I replace the cv axles right away? I'm not certain this is what needs to be replaced. Is slight movement in the CV normal?
Bumbed out

Usually you'll notice a clunking when you turn sharp corners at low speeds when you cv's go out. I'm wondering if it might be a bad ball joint. Also just check and make sure all your suspension bolts are tight, then try taking a sharp corner at like 5-10 mph in a parking lot, you should hear a clunking sound, if not, your cv's are probably fine and its a ball joint or bad bushing.