First few moments of the video render as just a black screen - Premiere Elements 9


First few moments of the video render as just a black screen - Premiere Elements 9
I'm putting together a short, 8-second demo clip of a particular moment of my project in Premiere Elements 9. The section involves two clips which were taken seperately, but are cut in half with the crop function so that they both play on the screen at once. There are also some position and brightness adjustments of one of the clips to ensure they match up.
However, I have begun seeing strange behaviour when I attempt to render the clip and as so far I have not been able to get a usable copy. When rendered as a .wmv, one of the two clips is inexplicably cropped from the bottom up to about a quarter of the height of the scene, despite not being so in the editor. Furthermore, when rendered as an MPEG, the format I would prefer the file to be in, although I do not get the first problem I get an issue where the first 20-23 frames of the video refuse to play in an external video player. I tried both windows media player and VLC. Instead, the section of the video appears as either a black screen, a black screen with a white line on it, or, if the video timeline is scrolled back to the start, the last frame viewed. The music clip which accompanies the video however still plays during this section, and the error is not seen at all in the editor. Oddly, if one of the rendered files is imported back into Premiere Elements 9, and played within the error, the 20-or-so frames will indeed play. It seems it is only the Premiere Elements editor that can play these frames.
I'm utterly at a loss here. I don't mind too much not being able to export as .wmv, as it is not my first choice, but if anyone could help me with the MPEG rendering I would be very grateful.
The source files are AVCHD (.mts) files, at a resolution of 1440x1080. There is only one "clip change" at the point where the video becomes viewable again, but this is merely where I have split the same clip to perform a brightness change, as I have many times in the video elsewhere.
Thank you for any help,
Here's a screencap of my interface, although I blurred out the video preview section (it doesn't contain anything relevant anyway).
I would like to avoid posting a copy of the video if I can help it - I doubt my actors would be too pleased with me posting them around the internet.
As for the project settings, when I first imported the clips Elements informed me that my project preset was incorrect for the clips and automatically picked one to fit them, so I'm sure that that's all set up fine. All the footage is from the same camcorder, except for a splash screen image, of the correct resolution, which flashes up at the end.
I have used assets of the same format previously and with no isses.
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