This is aimed at Premiere Pro, but may help
Work through all of the steps (ideas) listed at
If your problem isn't fixed after you follow all of the steps, report back with ALL OF THE DETAILS asked for in the FINALLY section at the troubleshooting link
You've hardly given us anything we can use to deduce your problem and help you, pf.
What kind of camcorder did your video come from and how did yout get it into your computer? Which project setting did you use in Premiere Elements? Are there red lines above your clips when you add them to your timeline?
Have you resized all of your photos to no larger than 1000x750 pixels in size? (Don't know if your books include the ones I've written -- but mine would certainly have helped you through these issues!)
How fast is your processor and how much RAM do you have? How much free, defragmented space is on your computer? What operating system are you using?
And which version of the progrm are you using?!
I had the same problem recently with PE9, although I had never seen it in older versions. Unfortunately I did not find anything to fix it either, nor have I been able to recreate the problem. Fortunately I had auto-save turned on and simply went back to the previous auto-saved version of the project and was able to continue from there. Sorry, this may not help you fix your problem but if you have auto-save on you may have an option there.