check firstly:
$ rpm -qa | grep eclipse eclipse-platform-3.4.2-20.fc11.i586 tomcat5-jasper-eclipse-5.5.27-6.2.fc11.noarch eclipse-pde-3.4.2-20.fc11.i586 eclipse-cdt-5.0.2-4.fc11.i586 eclipse-rcp-3.4.2-20.fc11.i586 eclipse-jdt-3.4.2-20.fc11.i586 icu4j-eclipse-3.8.1-5.fc11.i586 eclipse-swt-3.4.2-20.fc11.i586
...
1. uninstall eclipse on fedora 12
a. sudo yum remove 'eclipse*' ( This assumes you installed with the package manager or an RPM file )
b. make uninstall ( If you installed from source, then go to the source directory and run the command. don't know if that works, but it's worth a try )
2. install eclipse