Well, im getting a message everytime i want to open Revit Architecture 2011, it says "Revit could not load CONCEPTUALENERGYANALYSISDB.DLL", i already tried reinstalling the program and installing the most recent version of net framework and still getting the message, i can't use the program and i can't find what is the reason.
I had same situation w/the 64-bit Revit 2012 Arch software download from Subscription services.
The installer mistakenly believed (or didn't verify to begin with) that .NET Framework 4.0 had been installed.
It was not on the Win7 x64 SP1 PC at all.
Never saw this error on any flavor of Revit from 2010-2012 (installed from shipping media and/or deployment created from shipping media).
For me, installing .NET Framework 4.0 (Client AND Extended) resolved the error.
I know some of the more recent .NET updates have not played nicely with other non-Autodesk 3rd party software. I've only had to do it a couple times on my end, but I've seen some .NET Uninstallation utilities out there to pick up the slack Microsoft sometimes leaves behind... perhaps such a 'manual' uninstaller helps you out on this.?