Over the weekend I installed DOTLESS package into my ASP.NET Web Forms project. And I was testing the application without problems.

But today when I try to run/debug the project (without any major changes) I get the following error:

0x800a139e - Microsoft JScript runtime error: ASP.NET Ajax client-side framework failed to load.

The error is called by the following code:

<script src="/bundles/MsAjaxJs?v=J4joXQqg80Lks57qbGfUAfRLic3bXKGafmR6wE4CFtc1" type="text/javascript"></script>
<script type="text/javascript">
//<![CDATA[
if (typeof(Sys) === 'undefined') throw new Error('ASP.NET Ajax client-side framework failed to load.');
//]]>

Any suggestions to what causes and how to fix this issue?

UPDATE: some additional information. When I start/debug the project in Chrome, no problem. So the problem is only when I use IE (9.0).