I ran into an interesting problem while installing MDS on a customer machine this week. I installed SQL Server 2012 and Visual Studio 2012 on a Windows 7 box. When I tried to configure MDS, I got a warning that said some Web Server software wasn’t installed. After verifying that the list of things that MDS said it required was indeed installed, I decided I wasn’t going to be intimidated by a mere warning so I configured MDS anyway. This worked fine but when I tried to bring up the client I got an error that said the URL was invalid. I dug into the IIS configuration and found (with a little help) that the World Wide Web service was disabled. I’ve seen this before – a security policy on the network disables IIS periodically to keep people from starting their own web sites on the corporate network.When I enabled and started the World Wide Web service, I god an error that said a page handler wasn’t available. This appeared to be an ASP.Net problem. When I looked more into the IIS configuration I noticed the .Net 4 Application Pools weren’t there. After a bunch of messing around with settings, I finally did a “Repair” install of Visual Studio 2012. After this, the ASP.Net application pools were there and MDS ran fine. My assumption is the problem was caused by the Web Server being disabled when the 4.5 .Net framework was installed the first time. Not an earth shattering discovery but running into corporate security policies that disable web servers is pretty common so I hope this might save you an afternoon of tearing your hair out someday (yes, I’m officially blaming my shortage of hair on ASP.Net).