App launch stopped working. Error at compiling

[jpp1jpp1]

I'm already stuck for hours with this, please help me!

I can't figure what has changed. It must be something with my Eclipse installation, my run configuration or the tomcat server. When I get in development mode I get this error after opening the web page:

12:58:20.156 [ERROR] [appname] Failed to load module 'appname' from user agent 'Mozilla/5.0 (Windows NT 5.1; rv:5.0) Gecko/20100101 Firefox/5.0' at localhost:3499

java.lang.ClassFormatError: Invalid pc in LineNumberTable in class file org/eclipse/jdt/internal/compiler/lookup/TypeBinding
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
    at com.google.gwt.dev.javac.CompilationStateBuilder$CompileMoreLater.<init>(CompilationStateBuilder.java:153)
    at com.google.gwt.dev.javac.CompilationStateBuilder.doBuildFrom(CompilationStateBuilder.java:384)
    at com.google.gwt.dev.javac.CompilationStateBuilder.buildFrom(CompilationStateBuilder.java:299)
    at com.google.gwt.dev.cfg.ModuleDef.getCompilationState(ModuleDef.java:325)
    at com.google.gwt.dev.DevModeBase$UiBrowserWidgetHostImpl.createModuleSpaceHost(DevModeBase.java:105)
    at com.google.gwt.dev.shell.OophmSessionHandler.loadModule(OophmSessionHandler.java:190)
    at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:510)
    at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:352)
    at java.lang.Thread.run(Thread.java:662)

I haven't found anything in the web about this error. Any hint?

[jpp1jpp1]

Found the solution, this was a tricky one. You have to put the GWT lib first of all in the build path, and the error is gone.