What did you calculate or R2? **broken link removed**
I would not use a 430 uF cap on the output. Loose it, it's tough for the regulator to do it's job with that there. On PDF page 7, there are suggestions for the value and type of the bypass caps. Bypass caps should be located very close to the IC. The IC may be oscillating because of poor bypassing. Be aware that a minimum load is required, but th 120 resistor should take care of that.
There should be about 1.25 V across R1 or the 120 ohm resistor.