Try to press ‘F3’ at the boot menu (where you can choose to start the Live system or install f.e.) and choose “No KMS” (only available when not using UEFI), or press Shift+Alt+F12 to turn off compositing in KDE.
If you decide to install openSUSE, you can probably “fix” the underlying problem by installing the proper graphics driver (in case of NVidia or AMD cards).
This depends on which graphics card you are using of course.