Using JBoss 4.0.1, Eclipse 3.1.1 with JBoss IDE 1.5RC1, JDK 1.5.0-01b8

I start the server from the Server Navigator in Eclipse and hit some pages in my web app. If I make code changes and recompile, rebuild and redeploy my WAR (using an ant script) on the server while it is still running, I get obscure

java.lang.NoSuchMethodError: kh.weblog.db.BlogDAO.retrieveTopCategories()Ljava/util/Set;

exceptions, for methods that definitely exist. I get this exception even when the code changes are no way related to this one method. I get the same error if I redeploy even if there were no code changes.

If I stop and restart the server from the JBoss IDE, the exception goes away, until I hotdeploy the WAR again. This used to work fine with a previous version of the JBoss IDE.

I suspect this is a classloader issue, but I'm not sure where to start looking. This is a major annoyance as I cannot hotdeploy any code changes - I have to restart the server for every code change.

Any ideas?