Is this after a reboot of the server? I had this on a win 2008 R2 sp1 server, I saw a http 500 error.
I changed the mcafee services to "delayed start" and it's running fine again.
You may have a look at your IIS and see if the default web site is running on the same port as agent-to-server port (usually port 80). If so then stop the default web site or change its port to another one.