Doing a project which must be done by weekend. Imported numerous photographs which I have manipulated in Paintshop into the project media which show up fine, and even show up in the trimmer. When I put them on the timeline, some are fine, but a lot just show up as a red screen or sometimes a black screen. There is no pattern to it, some are colour and some are black and white. They all show up in the trimmer and the timeline, but when the cursor runs along, some will show in the preview screen, others not. What am I doing wrong, this is the first time that it has happened to me. Please help.