Try the following in order to troubleshoot
1- Add an empty html file to your deployed folder and try to browse it from webserver
a. If you receive the same error, you might have some problem with permissions try the following link:
<a href="http://support.microsoft.com/kb/842493">http:
b. If it works means you have some problem with configuration or installed frameworks so in order to check the IIS configuration try the following :
•In IIS Manager, expand the local computer, and then click Web Service Extensions
•In the details pane, check the items and their ‘allow and deny’ settings
And last step could be registering .net framework in IIS, but I think it’s not your case, because you already have running applications in that IIS server with same framework.