Help with a strange key combo that causes rapid move- dangerous..

[Rich05]

I use shift + pg up or shift + pg dwn to often move the z axis quickly into position. But there is another key combination that I hit by acident sometimes its cntrl+pg up or down. (i think)

this is the problem the mill moves about 4 inches in whatever direction when that key combo is hit, no way to stop it, this has broken a couple things.

is there a way to disable this? or what is this key combo about. its a real trap hitting that by accident since the shift is near the key.

thanks

[Mstcnc]

ctrl + page down or up or arrow keys are for jog for set distance.
you can change incremental jog distance from page which appears after you press tab key.
axis moves at jog speed which can also be changed from same place

Regards Mika