Extrude not working

I have a very simple project that has completely baffled me. An 85X85X20 box. I need round holes 4mm wide going straight thru and holes on the 3 surfaces for concentric circles of 9mm. I am having all kinds of trouble extending the 4mm holes thru the body. I cannot specify a length. I input -85 and execute and the window will show 15.1mm. If I drag the arrow, it will disregard my pull, unless it is under a certain distance. I am about to redo the whole project to see if I have tripped some preference that is stopping me. Thanks for any help

Hi Mark,
Can you atttach a screenshot?