iCal keeps prompting to "revert, edit, send."

I have a mac book pro that runs the latest version of El Capitan 10.11.2. My iCal is connected with a Microsoft Exchange 2010 account. Anytime I click on a different calendar item or event, I am prompted to "revert, edit, or send." I have unchecked under calendar preferences "ask before sending changes to events," I have restarted the Mac, disabled the account and re-enabled it, and finally I removed the exchange account all together and re-created it, but no change. Does anyone out there have an answer for this issue?

If more information is needed please let me know and I will answer promptly. Thank you very much.

aaronis83.