It seems you have also updated WTP to the 3.4.0 version (WTP Juno).
This is only possible if your distribution includes some Juno update site.
JBoss Tools 3.3.1 isn't compatible with WTP 3.4.0.
You can roll back the configuration to the configuration before updating JBoss Tools to 3.3.1, remove Juno update sites and update JBoss Tools again.