Libraries and class path JDeveloper Project Properties

We could not run the project for any reason.

When we check in Project properties, we see the Red and yellow warning signs.

The JDeveloper version is  11.1.2.2.0 and the project works perfectly today. 

An Unexpected Server error has occurred in JDeveloper

We are using JDeveloper version 11.1.2.2.0 and I have installed all the updates available.
Whenever restart the JDeveloper, the Unexpected Error appears.
An unexpected server error has occurred in JDeveloper
The program  may be unstable, which could result in data loss. Decide how you want to proceed and click OK.

Getting An Unexpected Server error has occurred in a popup and showing some option to continue,save all etc.,.

Wish to know reason to get when it appears  re-start the JDeveloper.

 According to John, it will be a  typed the error message from memory.
How to clear it?