You were using only 39% of your permgen when it was set to 256M, so upping it to 521M does no good. Increasing or decreasing the total heap size should not matter. Based on the error message: requested 35608 bytes for Chunk::new. Out of swap space? This means that the operating system refused to allocate more memory for the JVM when requested. I suspect a problem with the box you are running on, either a physical problem (bad RAM), a corrupted DLL, or possibly a corrupted driver. Do you have another box you can try this on? Also, the JVM should never crash regardless of what the Java application does. I doubt that there is anything that is done, or could be changed, in JBossAS 5.0, that would have any bearing on this issue. However, the JVM might crash if the operating system returns an unrecoverable error for a given operation, such as an error indicating a hardware or OS problem. Finally, since this is a JVM crash, you should report the crash to Sun. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4185423#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...