Ok so I finally got all my rotary stuff working and I was trying to tweek out the accel and velocity settings and I got everything running a lot faster with no missed steps when I manually jogged everything.
So I loaded up a file that is a 3d relief rastering across instead of around the work (have a small bit of flex in the belt when rastering around the work need to fix) and right off the bat motors stalling and going nuts
So did some reading here on the forum and tried all kinds of stuff.
During the process at one point I let it run stalling its self and went to adjust things and well when I went to the settings tab everything stopped stalling and ran great went back to program run screen and instantly everything starts stalling again switch back to settings tab and runs smooth.
So I restarted everything and as soon as I hit the program start button I switched to the settings tab and the whole program almost 1 hour long ran without a single problem.
I noticed during the testing that on the program run screen and the MDI screen which also stalls the motors that the box showing what line of code its on is not updating while running when you pause it jumps to the line that it is actually on.

Ok so this is a fresh install of XP computer and I dont remember what version of Mach is running but its an older one I will try updating it tonight and see if that works. I have plenty of motor power and all that its not mechanical or electrical it is in Mach and has something to do with displaying the run code I believe ( I did change the look ahead from the default to 200 trying to fix something previous could that have done it? Also this computer has plenty of power and memory kernel is set at 60K but could be lowered for the gearing used.

So any ideas what to do?

What or how do I update mach without loosing all my motor tuning, ports and pins, etc stuff.

Try turning off the toolpath.

Gerry
How do I do that?

I have to go back to work so I wont reply back until I get into the shop tonight and try stuff.

There's a button on the Diagnostic page I think.

Sorry for the late reply so turning off the toolpath did the trick not sure why as the computer is plenty fast and has plenty of ram

Anyways it fixed it the g code was a very long file 8 meg is a pretty big txt file 

thanks Gerry I guess I need to do a screen set with out the toolpath as I really don't need to see it anyways in fact I don't think I have ever really looked at the big ones for me are the 4 axis DROs and the line currently on (in case I need to know where or what is causing a problem if and when it happens).

This is a known issue with Mach3 and large g-code files. I turn mine off for files over 250,000 lines.