Wierd Z axis in EMC

Hi guys,

I have installed BDI EMC recently.
I just got it going OK I thought, but now seems to have gone off the
rails.

I have a Bridgeport mill (which I am in the process of completing
it's conversion to CNC),and am running steppers using freqmod, on a
300Mhz 64Mb M/c.
The drivers I am using are old STM103 (Superior Electric, I think)
cards.

The was machine running OK, and then without making any changes the Z
axis has gone mad.
When I try and jog the Z(say 180mm/min), it takes off at higher than
the max speed my setup is able to run at(ie. motors stall and get
following error). If I then reset the machine and try and jog the X
or Y, I get the same result, but if I haven't tried to jog the Z the
X and Y work as expected.

This is only a problem with EMC, as if I reboot in dos, the other CNC
programs(DeskncRt, TurboCNC) I have still work OK.


I am going to try another PC, as the one I have does have some
problems with the System Registry when loading Windows, I don't know
if this indicates a fault that would affect Linux/EMC..

Does anyone have any other suggestions that may be causing this
problem?

Any help would be appreciated.

Thanks
Tim Smith