STEVE: Well I assumed 4:3 aspect ratio is inn effect same? Do you think that
would prevent rendering if not exact?
You still haven't told me if you've resized your original photos to no larger than 1000x750 pixels. That's the first step.
Also, in Premiere Elements, ensure that the Work Area Bar (the light gray bar that runs along the "ticker" line on the timeline) is extended over your entire project. To set it so that it is, press the \ key to zoom out and show your entire timeline and then double-click on the ticker line along the top of the timeline.