java.util.ConcurrentModificationException after installing GWT 2.2

[tdk]

After installing GWT 2.2.0 I keep getting the following error when
trying to start my app in Dev Mode:

init:
deps-module-jar:
deps-ear-jar:
deps-jar:
library-inclusion-in-archive:
library-inclusion-in-manifest:
Compiling 2 source files to C:\Development\IcsContinuity\Webinterface
\build\web\WEB-INF\classes
compile:
compile-jsps:
debug-connect-gwt-shell-hosted:
GWT4NB https://gwt4nb.dev.java.net
GWT installation directory: C:\opt\gwt\gwt-2.2.0
init:
debug-connect-gwt-shell-hosted-15:
init:
debug-connect-gwt-shell-hosted-16:
init:
debug-connect-gwt-shell-hosted-17:
init:
debug-connect-gwt-shell-hosted-20:
Waiting for the output from the GWT dev mode...
Waiting for the output from the GWT dev mode...
Waiting for the output from the GWT dev mode...
Browsing: http://127.0.0.1:8888/Portal.html?Obj=98895029.13@team128&Act=894.1256@0001?gwt.codesvr=127.0.0.1:9997
java.util.ConcurrentModificationException
java.util.ConcurrentModificationException
at java.util.LinkedHashMap
$LinkedHashIterator.nextEntry(LinkedHashMap.java:373)
at java.util.LinkedHashMap
$ValueIterator.next(LinkedHashMap.java:388)
at com.google.gwt.dev.DevMode.doSlowStartup(DevMode.java:386)
at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:
1086)
at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:800)
at com.google.gwt.dev.DevMode.main(DevMode.java:304)
BUILD SUCCESSFUL (total time: 38 seconds)

Anyone knows what this means, what it is caused by?

I'm using Netbeans 6.9.1, Gwt4NB 2.10, SmartGWT 2.4, Firefox 3.6.13,
Vista Business x64