Did you remove the communications cable and try rebooting? Is it a known good cable, properly wired? Most of the time, an incorrect cable just prevents communication from occurring, it doesn't fry anything, but who knows?
Did you accidentally hook the comm cable to a pc printer port (don't laugh, it is possible )
I'm just imagining the things that a newb can suffer through
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)