A black screen issue with Custom Resolution Utility (CRU) usually occurs when an unsupported resolution or refresh rate is applied to a display. This happens when the monitor or graphics card cannot handle the custom settings, causing the screen to go blank or lose signal. Common reasons include incorrect timing parameters, exceeding the monitor’s refresh rate limit, or using incompatible resolution settings.

To fix the CRU black screen problem, users can restart Windows in Safe Mode, run the reset-all.exe file included with CRU to restore default display settings, and then reapply safe custom resolutions. It’s always recommended to test new resolutions carefully and increase values gradually to avoid display loss.