I am using a UC-100 to connect the cnc with the HP PC. it's running Win8.1. When I boot the software the UC-100 led lights go on (gree, blue solid).  I can see the UC-100 in it's monitoring window.  The only thing that works is the estop.  I can click on reset and the blinking goes away.  Is there anything in the settings input, outputs etc., that could be enterer wrong?  I have tried alot.  Can someone please help me to setup my 3040t CNC!  I think it should work! 
Thanks,
Tom Megna

Looking at the UC100 docs, a blinking blue and only Estop working appears to be a CPU load issue.
What is shown in the mach3 status window.. UC100 sync error?

Have you setup Mach3 with proper port/pins etc... correctly?

looking at the UC monitor window, can you see any of the mach3 functions working while using the mach3 control screen?