This project in the CVS had the default Java Builder deleted and replaced by the ant build. I wanted to revert back to the default Java builder.
The java builder used by eclipse is org.eclipse.jdt.core.javabuilder.
Anyway , my solution to the problem is include the following in the .project file :
<buildSpec>
<buildCommand>
<name>org.eclipse.jdt.core.javabuilder</name>
<arguments>
</arguments>
</buildCommand>
</buildSpec>
<natures>
<nature>org.eclipse.jdt.core.javanature</nature>
</natures>
Thanks a lot.
Kapil