I have recently experienced a JavaScript errror incident when I started using Roles and Membership in a website for the first time.

IE6 reported a syntax error at Line 5 after adding a SiteMapDataSource and Asp.Net Menu controls to the page. The menu would not work I guess due to the JavaScript error.

A quick Google, led me to this page which led me to try adding the following code into my web config

  </system.web>
  
  <!-- Prevent JavaScript Errors, caused by web resource can't be accessed by current user. -->
  <location path="webresource.axd">
    <system.web>
      <authorization>
        <allow users="*"/>
      </authorization>
    </system.web>
  </location> 

</configuration>

This appeared to remove the error, I am assuming by allowing the web resource JavaScript to be accessed by all users.