weird behavior

I have been using the Debian Wheezy version for some time without problems and suddenly I get this weird behavior.

%
g01 g40 g49 f100.00
(93493 5.930 long)
g90 x0.5 y1.000 f100
g90 z0.02 f100
g90 z-0.02 f0.1
g90 z0.02 f100
g90 x1.500 y1.0 f100
g90 z0.02 f100
g90 z-0.02 f0.1
g90 z0.02 f100
g90 x4.530 y1.0 f100
g90 z0.02 f100
g90 z-0.02 f0.1
g90 z0.02 f100
g90 x0 y0 z2 f100
%

When I step through it, g90 z0.02 f100 only moves z to 0.00. The subsequent command actually moves to z0.02.The g90 x4.530 y1.0 f100 actually takes me to x4.530 y0.75. Is there something magical I should be looking for? Entering commands through MDI gives similar results. It really helps when the mill vise is aligned correctly with the table! Solves the Y axis, problem but not z0.02 not taking effect until next command.

Have you tried reducing the speed? Perhaps f50 instead of f100 on the problem moves?
Is G61, G64 set?
linuxcnc.org/docs/html/gcode/g-code.html#gcode:g64

Rick G

The DRO is reporting actualposition. Should I try commanded position instead?

I will try those. Thanks.

Not sure. Sherline 5400 CNC.