What program are you using ad what computer operating system is in use?
If you are working with Photoshop Elements or Photoshop, you have posted in the wrong forum. Some how your thread got posted in the Adobe Premiere Elements Forum (video editing). If that is the case, please re-post your thread in the Adobe Photoshop Elements Forum to take advantage of the specialized expertise there.
When you re-post your problem there, please give lots of details including program, computer operating system with resources described, pixel dimension of the photos and how many of them are there, type of edits applied to the photos....