I am fairly new to C programming and have been using a free compiler recommended by my instructor, called C-Free Standard 4.0.

I have been experiencing a problem where when I type code for my homework problems, and work out all my errors, then save the program, from then on when I run the program new errors that didn't exist before suddenly appear and jack up my program.

If I change nothing, cut and paste the code to a new unsaved/untitled sheet, I can run it (Press F5) without error as before. But as soon as I save that the same thing occurs.

These symptoms appeared weirdly. I had a program working, then saved it, turned it in electronically, and when it was graded the instructor commented that he had parse errors. They did not appear for me. The next assignment, I was having issues with an error that wouldn't go away, until I saved it. Then that error went away and was replaced with others that I was able to resolve. but once again, I submitted the assignment and the instructor had errors. When I reopened the program, I too had the errors. The next assignment began regular, repeatable problems describe in paragraph 2 and 3 above. My instructor had me re-submit the errorring programs as word documents so he could look at the code, which he found no problems with, and copied it into his compiler with no errors.

I've tried deleting and re-installing the compiler a couple of times, with no change. I've run virus scans and found nothing.

Any idea what's happening?