I'm working on a client's domain. I have 2 IIS 7.5 boxes running various host headers with MVC 4 applications using domain account app pool identities. The sites running .Net 4.0 run fine, however when I put a project created in VS2012 MVC 4 .Net 4.5 under a new host header yesterday, the app ran until it failed at a .Net 4.5 method call (giving a missing method exception). .Net 4.5 is installed on the boxes. Anyway nothing (inc registry changes, reinstalling 4.5 etc) would get this app to work. I also began to see errors in the event logs about not being able to ping the app pool account and that certain directories could not be found.
This morning as a desperate measure I installed VS Express 2012 on one of the boxes and bingo everything started working on that box. Has anyone come across anything like this before as putting VS on a server isn't really a "good" idea?