Why does acrobat keep crashing on me?

I have used my acrobat both on my laptop and my desk top computer. Both times, while filling out an important pdf document for HOURS it eventually stops allowing me to edit, and then two messages start on the screen. One says "Preparing file to edit" over and over again and the other says "Saving Changes" over and over again. I can do nothing with the file at that point! It won't even let me print it out! I am at my wit's end and cannot spend more valuable time retyping this important document. If anyone has a fix, please I beg for your help!