There is a sample of this problem in this video
http://www.youtube.com/watch?v=55cW9VtP5G4
at 12:27 into the video (go to about 12:20 and hit play).
It happens in both preview mode and with rendering the output. It is very random usually, but in this project it always occurs at this point in the video (solid failure). Degree of which depends on resolution of preview. Small preview gives random black transitions at this point every time. "Launch media viewer" and previewing in full screen results in the blue screen of death on my PC. I have not test it, but I doubt if this problem would occur rendering to say WMV, which does not use hardware acceleration.
It might be related to video driver and/or multi cpu cores (multi threading). Turning off hardware acceleration seems to prevent the problem (has not occured on this test video with acceleration turned off).
I'm about to upgrade to Windows 7 on a new hard drive, and will test this failure again afterward. My version is PD 9.0.0.2702
I have opened 14 trouble tickets on PD since 08/2009, none of which have resulted in a resolution. CB supports assumes their product is perfect, so if you are submitting a problem report it must be user error. Having even pressed some of these tickets up to 2nd level phone support, and never getting a "you're right, we must have a problem" attitude back from CB, I don't think I'll bother jousting at this windmill.
To CB's credit, I own Sony Vegas, Pinnacle VideoStudio, and Corel VideoStudio X3 in addition to PowerDirector, and even though PD is the buggiest of the four product by far, it's what I always turn to for "post production". Why? In spite of having to use a crowbar to get through a project, a better end product can be created in less time.