This exact same thing is happening to me as well. I downloaded PowerDirector 11 yesterday, and applied the build 2215 software update. I'm editting an MOV file (1920x1080), and every so often after I split a clip and/or delete an unwanted section of the video in the timeline, the preview window goes all green. Sometimes it fixes itself after jumping around the timeline, but usually I need to restart the program. Worst of all, when I go to Produce the finished product (WMV file, HD, 1920x1080), the resulting video has sections that cause the video to go all green too. When I go to Produce it again, that green screen occurs in a completely different section.
I disabled Continuous Thumbnails, and I tried it with both HW decode enabled and disabled, and it still happens. This is very frustrating since I do a lot of video editting, and this has put me behind on my projects. Are there any other suggestions on how to resolve this, or maybe this is being looked at for a bug fix patch?