When using Sun JDK 1.5 to run Eclipse 3.1M5a, using JBoss IDE downloaded through the eclipse Update function, the "-vmargs -noverify" flag must be used to prevent a verify error when pulling up the XML editor. When run with this flag and editing an XML file using the JBoss IDE XML editor, saving the XML document causes eclipse to crash.

I've tested this on Gentoo Linux/GTK Eclipse 3.1M5a and WinXP Eclipse 3.1M5a with the same version of JBossIDE in both. It happens every time, for every kind of XML file.