another 'unknown error' on save for web jpg

I have still been running Illustrator CS5.1 for numerous years with no problem. I used in a previous life and now only here and there.

I have never had a problem saving files until a few days ago.

Last month I finally upgraded from my desktop version of Lightroom to Lightroom Classic/CC. I am stating this as I believe this may be the first time I have used Illustrator CS5.1 since I upgraded Lightroom. And can only think that something about that upgrade is somehow conflicting with my old application(s).

I have no issues saving the files in .ai. The problem is only when I go to save for web and try to save as png or jpg.

I did see numerous posts regarding this issue point to problems with hidden or locked files, corrupted fonts etc. I tried deleting all hidden layers, nothing is locked. I created a brand new file as well and the same problem exists.

I did finally discover those that as long as I have not saved the file yet in Illustrious format, it does allow me to save for web as jpg without error. Once I save the illustrator file and then try to save for web I receive the error. This was fine for a small project and quick word image, I create a new file and added my text, and without saving went to save for web.

This is not a solution I can work with though. I know CS5 is old and Im sure there is no support for me here on it but if anyone has an idea?

Im also not an expert user, I know enough to get into trouble

thanks

Jennifer