Hello Everyone , I have downloaded the new 3.8.26 software on my shopbot prt 96x48 with an upgrade RPK control box. Machine had been running fine untill it went to home and i loaded another file and the computer could not find machine . The problem i am having the machine runs a couple of passes ok and then the carriage will start jumping. The Z axes going up and down will jump. When i go into preview mode a box come up saying Failed to open preview data file. I have dumped every file i can find and tried downloading the software again. I have run UR, UI Each time. I called Shopbot this morning to make sure i was loading the right machine for the RPK control box and they said it was right PRT Standard ToolV4Gorv RPK Upgrade. Thanks again for all your help.