JBoss Tools 3.1.1 isn't compatible with Helios.
If you want to use Helios, you need to install JBos Tools 3.2.0 (http://download.jboss.org/jbosstools/updates/nightly/trunk/) and webtools 3.2.1 (http://download.eclipse.org/webtools/downloads/drops/R3.2.1/R-3.2.1-20100730021206/ or http://download.eclipse.org/webtools/repository/helios/) that fixed some performance issues.
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