Been using PE9 for a few weeks and within the past couple of days it seems to get confused about which image should be displayed within the timeline. Have a medium size project with 30-40 jpg's in it and when shown in the timeline (or in the monitor window), PE9 replaces the image associated with a particular file with an image from another file. In the Project list you can get Properties and the path\file name shows up perfectly but PE9 uses the image from another file. Tried closing the project, and PE9 - no help. Tried re-booting Windows 7 (64 bit) - nop help. This seems to get worse as time goes on and I have not been able to find a solution.
Does this happen even if you ensure all of your photos are no larger than 1000x750 pixels in size?
My photo's are either 720 x 480 or 720 x 1080 depending on whether they are landscape or portrait.
It might be worth contacting Adobe about. I don't know what would cause that kind of behavior. Sorry.