@Tim-Franks Support has about two thousand open tickets. We received this information a few weeks ago, so it might take some time. Basically, it's enough to write to infoservice@magix.net and tell them you want to return the software. But unfortunately, I can't say when or if someone will respond. Perhaps, in the meantime, we can also help and offer some tips to make the program run normally. For example, if Windows creates a crash report in the Windows Reliability Monitor, you can copy and paste it here.
As @SP. has suggested, if you would like help to determine what the issue is and possible fix, then in addition to the Reliability monitor information, we need more information,
The specification of your computer system including Windows version and program version, see this topic for what is required and please quote processor and graphics card make/model in full, and also what monitor/screen resolution(s) you are working with if this is a laptop.
If the issues occur when adding video to the timeline.
Download and install MediaInfo and analyse one of the clips and post the results, see this tutorial on how to setup MediaInfo and analyse a video clip for all the data required.
The amount of free space on the hard drive(s) you have.
Are you getting any error messages, if so then please quote them in full or provide screen shots.
Are the graphics card/integrated GPU drivers up to date?
A screen shot of the Program settings, Device options tab would help.