When I developed a TV project, something strange really bothered me for weeks. The CRT (Cathode Ray Tube) TV project was based upon a Philips 8051 TV microcontroller with on-chip OSD (On Screen Display) and Tuning features. The software was running on my emulator without any problems. So our customer decided to launch pilot production. The QA team found something strange in the internal audit procedure and notified me urgently. Among 12 TV sets, about 5 TV sets randomly shown the retrace scanning lines after AC switching on. The occurrence was unpredictable.