How much free memory do you have available (before running Eclipse)? Did you also increase the permgen size? The JVM will refuse to run if it determines there is not enough memory to allocate the heap and permgen. If you have plenty of memory, you might want to play around with the permgen size and max heap size to find a workable combination. It might also help to monitor the heap usage for your original settings. A tool such as jconsole or visualvm should help with that. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4264648#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...