If I jog the router around before I load a large file (3D file for lithophane) everything works fine. After the file is loaded, if I make movements the router will continue to run for approx. .25" on any axis. Is this a memory problem with the computer? My comp is a PIII 850mhz with 256meg ram and nothing else installed on it. I don't have this problem with small files. Are there any settings I could check? Now I just zero all axis before I load the file to eliminate tool breakage.

Use task manager and check memory and cpu usage.

I noticed this too....I changed jog follow or display mode, and it stopped that.