Fluent NHibernate - Castle Dynamic Proxy - trust issue on localhost

A while ba开发者_如何学运维ck I had a problem running an app using NHibernate on the production box. The answer (thanks to stackoverflow - questions/1469408/) was to change to full trust. This worked great - however now I am trying to run the same application on IIS7.5 on localhost and am having the same problem. The .Net trust level is set to "full internal" so there shouldn't be a problem. Has anyone else ran into this problem? And if so, what was your resolution.

Any help much appreciated.

Setting the application pool to LocalSystem fixed it. http://blog.igorware.com/2009/10/login-failed-for-user-iis.html