MAX756 and Standalone Arduino

I hooked up the my MAX756 to Arduino running 5V. It would not work at all. I was reading 5V out with DMM but nothing. The reading did not appear to be fluctuating at all, so I know the arduino was taking a lot of Current which would drop the voltage. I eventually, put a capacitor across the V and ground and the system worked. I do not know how or why, the original setup didnt work. Or why or how I would have known without luck that i needed a capacitor there. I am using the 16mh resonator and not a crystal for the standalone. The resonator shouldnt need capacitors from the sketch I have. Any ideas?

3-pin resonator? If not, you need caps.

That IC is a switching regulator. You need caps on the input and output side. Without, it may be unstable, or switching noise could cause all kinds of problems. The typical application diagram suggests using a coil as well, so chances are the output is not quite DC, even if your voltmeter averages it out as such. (I've never used one of these, and haven't read the datasheet, so I could be full of it -- but it would explain your results.)