Sounds like the file is not correct format. Did you first save it and try to open it or worse did you verify the email sender is sending legit and not malicious email attachments?

NOPE--- It from people in my business, through our office email...ALWAYS worked until 3-4 weeks ago....NOW I cannot open anything.....

Did you save it and then open it to find out if it works or is a file issue?

I can save it to open..BUT, my question is STILL...why cannot I not just open it without saving?? what changed with mozilla??