ASP.Net & Ajax failed to load in Firefox

Question

Hello all. I've been racking my brains over this for a while and have resorted to asking you guys. I'm trying to get Ajax working on my ASP.Net website..
Internet explorer and chrome both work fine on my PC. Firefox on the otherhand (v 3.6.6) fails to load ASP.Net ajax client-side framework.
It falls on the ScriptManager object not defining "Sys".
The serverside development line is as follows:

<asp:ScriptManager ID="SM_ControlManager" EnablePageMethods="true" runat="server" />

the html code views as so:

<script src="/ScriptResource.axd?d=FGouPQaCgJN75GJBkqN7Z0D8qRrV3AXxqiRMol_JLzU8MvgOgmCKVwoGjZ1L4qJkjXbD5Q875jjRVCYvIgBsaKEbVNkLb7qAJTQoLRyFAEA1&amp;t=78ed6222" type="text/javascript">
</script>
<script type="text/javascript">
if (typeof(Sys) === 'undefined') throw new Error('ASP.NET Ajax client-side framework failed to load.');
</script>

Sys always ends up undefined.. but only on firefox. Any light to be shed one way or another will be most appreciated! Thanks a lot!

Answer 1

Self fixed with help from Darin Dimitrov. Rather careless on my part. in web.config the httphandler i added for it:

<add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.0.0, Culture=neutral, 
PublicKeyToken=31bf3856ad364e35" validate="false" />

the version for it is old and didnt exist on my server. replacing with:

<add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, 
PublicKeyToken=31bf3856ad364e35" validate="false" />

It now runs on firefox absolutely fine. Huzzah for carelessness, and thanks to Darin Dimitrov for making me attempt to browse to the src and read the error there. :)