Hi, am running mach3 with a Dell optiplex GX260 with non integrated graphic board with 32 mb ram. It exceeds the requirements for mach 3 but it keeps freezing. It does this whether or not the the parallel cable is connected to the breakout board. When it freezes not even ctr alt del will free it I have to button it. Before I used it for mach3 it was running perfectly. Any ideas anybody or do I have to get another pc ?

Try doing the optimisation steps detailed on the downloads page.
Hood

When you say optimisation what exactly do you mean ? Have set all the motor and switch pins so that everything works as it should and run the test which showed a flat line with no spikes and reported that it was excellent. It has occurred to me that the only change I made was to use a smaller usb keyboard so will revert back to my old one and see if that helps.

Look on the downloads page http://www.machsupport.com/downloads.php three or four up from the bottom of the page you will see a document with the optimisation steps you can do.
Hood