Lew,
To make the jog keys less touchy, lower the number where the cursor is at in this screen shot. Put your mouse over the box and click, enter number and press enter. This sets your slow jog rate. To rapid jog, hold down the shift key and then jog. You pull this screen up by hitting the tab key. What version of Mach are you running? Can you post the code that it is messing up on and notes on the lines where you stop and where it jumps to. Also, how do you pause the program? Feed hold or stop?
Brett