Hello
Last December I bought a kit Nema23 Stepper Motor Kit 4Nm x 3 Axis in cnc4you.co.uk, the breakout board included is the HG07

I was mounting my machine and let it finished last Friday. I did all the tests on Friday and leave it running ok. Today to go to work with it does not work.
 First I ruled out software problems, proving two computers and making all possible optimizations.
I have positive proof the parallel port and cable. with the tester. It seems the problem is the breakout board. When connecting goes well for a while but after a moment the problems begin. The power LED does blink, the motor stop at the middle of displacement, interrupts coincide with the LED off. Other times the engine is very slow ... Don't understand how it is possible that the breakout board stop working and now doesn't work without any changes.
Any solutions?

Sorry for my poor english

Probably best to contact the people you bought the Breakout from, could well be a Chinese one and they can be like that, work one minute then not the next.
Hood

Heat and or bad solder joints can cause problems like that too.