my imac freezes whenever i try to save a pdf file.

Try using Safari, if it works okay then ensure Chrome is up-to-date and if it is you can attempt to restart in Safe Mode (Use safe mode to isolate issues with your Mac) and then restart normally and re-test.

Sue, what exact path are you trying to save to & which App are you using?

Thank you so much for your advice. Saving under Safari worked perfectly with absolutely no freezing problems.