This may not be the place to post this...( please advise)  I have been using mach3 to run my 4x8 CNC router for a few years( LOVE IT) But i just swapped out computers to a HP with windows 10. and copied all my files over. it works as before flawlessly. however when I send a file to run the screen goes blank. CNC runs as normal but the screen comes on and off randomly. if you mouse is hovered over any of the buttons even though you an see them they work? has anyone seen this issue???

Try turning OFF Toolpath Display (Diagnostics screen).
If this makes a difference then it would suggest you need more graphics memory.

Tweakie.

Thanks Tweakie,
I just tried that, but with no avail.  still happening...i think ill toss a dedicated video card in it and go to serial

I had similar case. Switched to HDMI video cable. When running the program screen went blank. I found out that screen actually goes blank when starting the spindle, so maybe there was some interference from VFD, maybe through ground. After taking electricity from another socket problem was gone.