Casio HK1223 - Manual (Page 110)

6-8 Installing Software Drivers
2. When you use Windows Media Player to play a video file, the screen many flashes
ina very short time. This behavior can occur if there are problem with video. To
resolve the issue, you could set the configuration in Windows Media Player, use the
following steps:
Step 1. In Windows Media Player, SLECT[Tools] -Æ [Options….] on menu.
Step 2. SELECT [ Performance] Æ Click [Advanced….]