The only reason why a .prn file would be produced would be if you have selected the option to print to file.
Go through all the options available from the print dialog and you will likely find a dialog in which there is a print to file option that unintentionally got enabled (with a check mark). Uncheck the option and this problem should go away.
Just want to thank you for this answer! So simple, yet has eluded me for months! Gracias!
I don't have print to file selected and it still tries to save as prn it worked fine until 2 days ago I've even unistalled and reinstalled Adobe same thing happens now I can't print anything
Please show a screen shot of your Print dialog, and the Advanced box from the Print dialog. Perhaps there is another clue there.
I was having this exact same issue. I found the setting at Ctrl+P>Advanced. Here there was a checkbox marked "print to file"... thank you all so much!!!