I have had this problem from time to time and I found either, make sure the image has .jpg after it before posting, or as fourwinds said make the photo smaller.
I don't know what I'm doing wrong. I'm in the Camera's FINEPIX program and when I hover the mouse over the image it tells me it's a JPEG and I'm going to save as and as EXIF JPEG fine. But when I go back into the folder I've saved them in it says it's a paint shop photo album 5 pic.