I would ask you to verify which button you are pushing...
The reboot button is broken in the 0.7.5 firmware (hangs requiring power cycle), but fixed in subsequent releases.
I personally had not heard of problems with the reset button, which just sends an interrupt to the sketch loader.
You mighty just be the first person reporting it.
I'd second that opinion. That may also be a sketch - just a wild guess - not behaving after a couple of restarts... Or these are different sketches you're trying with?