What model of camcorder is your video coming from and what format is it?
If you're using photos, have you ensured that none are larger than 1000x750 pixels in size?
When you set up your Premiere Elements project, which settings did you select? If you've selected the correcdt settings there will be no red lines above your clips when you add them to your timeline unless they are photos. Is that the case in your project?
When do see red lines above your clips, have you pressed Enter to render your timeline?
Welcome to the forum.
Though it is mostly PC-centric (that is all that I use), this ARTICLE might offer some tips, that will also apply to the Mac.
With crashes, where one only has Still Images, I would definitely look to John T's links, as one is always best doing all Still Image Scaling in PS, or PSElements, prior to Importing into PrE. Besides lowering the resource overhead when processing overly-large Still Images, the quality will also be improved.
Good luck, and please let us know a bit more about your Still Images, and the Project's Preset, chosen at New Project (per Steve's questions). Also, Steve is our resident Mac-guru, as he is fully X-platform, and can help translate the suggestions in my link above to that platform.