PermGen Space eclipse
One of the reason is due to changes in "Java 6u21 distribution"
The change was done in "java.dll" to replace "Sun MicroSystems" to "Oracle Corporation"
Solutions :
1, Degrade to java 6u20 version
2, Create a shortcut of eclipse.exe (For eg., Desktop shortcut) , right-click on the shortcut icon and click properties , properties dialog will appear , find the field 'target' and modify PermGen Space by starting eclipse with "-vmargs -XX:PermSize=64M -XX:MaxPermSize=128M" as below
eclipse -vmargs -XX:PermSize=64M -XX:MaxPermSize=128M