Struts2 timeout during validation

I get a TimeOut error when I try to validate my login form BUT only the first time. Could you tell me what I'm doing wrong?

My [...]-validation.xml :

<!DOCTYPE validators PUBLIC "-//Apache Struts//XWork Validator 1.0.2//EN" 
                            "http://struts.apache.org/dtds/xwork-validator-1.0.2.dtd">
<validators>
     <field name="identifiant">
         <field-validator type="requiredstring">
              <message>Veuillez saisir votre identifiant</message>
         </field-validator>
    </field>
    <field name="motDePasse">
         <field-validator type="requiredstring">
              <message>Veuillez saisir votre mot de passe</message>
         </field-validator>
    </field>
</validators>

The stackTrace :

[com.opensymphony.xwork2.validator.AnnotationActionValidatorManager]
**Caught exception while loading file com/myApp/action/LoginAction-validation.xml
    Connection timed out** - [unknown location]
            at com.opensymphony.xwork2.util.DomHelper.parse(DomHelper.java:119)
            at com.opensymphony.xwork2.validator.DefaultValidatorFileParser.parseActionValidatorConfigs(DefaultValidatorFileParser.java:82)
            at com.opensymphony.xwork2.validator.AnnotationActionValidatorManager.loadFile(AnnotationActionValidatorManager.java:394)
            [...]
    Caused by: java.net.ConnectException: Connection timed out
            at java.net.PlainSocketImpl.socketConnect(Native Method)
            at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345)
            at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
            {...]

The server was not able to access to Internet. So the DTD had to be copied and referenced locally.

Thanks to Roman C. for the clue.