vfd will work in demo mode but not in real mode

I have a mill that I run with uccnc , a few weeks ago I lost my old 20 years+ computer, I put another newer one about 12 years old but with win 7 instead of xp.
I can get everything to run fine, except the vfd. I use rs485 control. it worked wonderful before for over 4years when I switched to uccnc. But now I can not get it to run for more than around 5 sec and the lost signial faught comes on. But here is the kicker, I can run it in the Demo mode and the spindle will turn on and off I can adjust the speed up and down and put in MDI commands and change the speed, but as soon as I go into machine control mode it does the same quiting. Any one got any ideas,

Sam