Ajax Error - doing anything!

I can not create, save, do anything. The error message is simply "Ajax error while saving form" or "Ajax error while adding field". I've tried deactivating all other plugins and also re-downloading and installing Gravity Forms. Nothing works. Have used GF before on other sites without these problems before. This simple error message is not helpful as I have no idea how to correct. Please help!

Just a heads up... I ran into this issue with one of my sites today. I already had 4 Gravity forms running on it but needed to add another. Found out I couldn't do anything. Couldn't add a new form or fields to the new form. Then I checked to see if I could add/remove fields form other forms that seemed to be working properly. Nope. Kept getting an AJAX error.

I deactivated all plugins (including Gravity Forms). Then I reactivated them all one by one and tested adding new fields to a form after each reactivation. Got to the end of my 15 plugins and all works now. Not sure what was going on but didn't have to remove any plugins. Just had to deactivate all of them and then reactivate them all. Now everything is working as it should again. Anyway... if anyone is having this issue, just give deactivating and reactivating your plugins a try. Maybe it'll work for you too.