Sorry you are experiencing this. I know it is frustrating.
There are a number of factors that can cause this type of problem. Please go to
this web page, scroll down to "How To Make Good Karaoke CDG Discs" and read the points.
Make sure to clean your original discs as best you can. If they are VERY scratched, it might cause Microstudio to lock up, but it shouldn't. I expect the media you are using is the main cause.
Please post back here what you discover.