Problems with gwt 1.5

[MikeTheQuick]

Hi.. i have a problem with the new gwt library...

When i compile my gwt application i have this error :

java.lang.VerifyError: Cannot inherit from final class
[java] at java.lang.ClassLoader.defineClass1(Native Method)
[java] at java.lang.ClassLoader.defineClass(Unknown Source)
[java] at java.security.SecureClassLoader.defineClass(Unknown
Source)
[java] at java.net.URLClassLoader.defineClass(Unknown Source)
[java] at java.net.URLClassLoader.access$000(Unknown Source)
[java] at java.net.URLClassLoader$1.run(Unknown Source)
[java] at java.security.AccessController.doPrivileged(Native
Method)
[java] at java.net.URLClassLoader.findClass(Unknown Source)
[java] at java.lang.ClassLoader.loadClass(Unknown Source)
[java] at sun.misc.Launcher$AppClassLoader.loadClass(Unknown
Source)
[java] at java.lang.ClassLoader.loadClass(Unknown Source)
[java] at java.lang.ClassLoader.loadClassInternal(Unknown
Source)
[java] Exception in thread "main"

The only things i changed are the gwt libraries....

With gwt 1.4 I don't have this problem... can someone tell me the
reason?

[Reinier Zwitserloot]

Your classpath is screwed up. Half the classes are being loaded from
an older version of GWT, and half are loaded from a newer version.

Double check your classpath; possibly you're picking up a gwt-user.jar
from one place and a gwt-dev-XYZ.jar from another. If you installed
GWT 1.5 by unzipping over the previous version, perhaps you unpacked
gwt-user.jar at some point to hack around with some of the code. At
any rate, try and install GWT 1.5 by deleting what's there first, then
unzipping.