GENERATE-ALL loader constraint violation ?!

It's my first post here so hello everyone!

I've searched for an answer already on the forum and googled it several times but I haven't had any sucess with the answers I found.

I have created a Domain Class without any problems. Then (in STS) when I try to GENERATE-ALL (the same happens to GENERATE-VIEW) for that class, nor the controller and view gets is created and STS throws this error:

Command terminated with an error code (see details for output)
------System.out:-----------
| Loading Grails 2.0.4
| Configuring classpath.
| Environment set to development.....
| Packaging Grails application.....
| Compiling 2 source files.....
| Packaging Grails application.
| Compiling 2 source files.....
| Error Error executing script GenerateAll: loader constraint violation: when resolving overridden method "org.apache.xerces.jaxp.SAXParserImpl.getParser()L org/xml/sax/Parser;" the class loader (instance of org/codehaus/groovy/grails/cli/support/GrailsRootLoader) of the current class, org/apache/xerces/jaxp/SAXParserImpl, and its superclass loader (instance of <bootloader>), have different Class objects for the type s.jaxp.SAXParserImpl.getParser()Lorg/xml/sax/Parser; used in the signature (Use --stacktrace to see the full trace)
------System.err:-----------

I'm really lost here and I dunno what to do. Already used the Refresh Dependencies option os several other configurations under BuildConfig.groovy.

Please Help..!

Thanks in advance! Best Regards,

André Baptista.