Sounds like something got hosed up on the CNC control computer. If you didn't remove the workpiece from the spoilboard you can probably just re-zero everything and start over. It won't cut anything for a while but it should when it gets to the remaining text.Finally, closed UGS and the spindle stopped!
I'm curious what text takes an hour to engrave; got any photos? What speed is your feedrate? What bit and wood are you using?