the error:"Referenced file contains errors (http://www.springframework.org/schema/beans/spring-beans-4.0.xsd)"

The error message is:

Referenced file contains errors (http://www.springframework.org/schema/beans/spring-beans-4.0.xsd).

A related link:  http://stackoverflow.com/questions/7267341/validation-error-of-spring-beans-schema-inside-application-context
In summary, the error may be resolved by doing the following:
" It was caused by some cached files. After removing those items (Preferences -> General -> Network Connections -> Cache) everything worked as expected. "
However, in my condition it was not helpful :( Another cause is using different versions together as stated:
"This error may have appeared because you had a mix of 2.5 xsd and 3.0 xsd in your applicationContext.xml. "
When i removed the version info from every element in xsi:schemaLocation, the project compiled successfully..