Greetings all, I've seen posts here in the past from those who've had failures compiling (fairly complex) code that uses MPL on Microsoft Visual Studio 2003 and later. On VS 2003, the compiler says that it had an internal error, but on 2005, the error looks like this: File name: fatal error C1060: compiler is out of heap space Happily, Microsoft has published a hotfix for the problem on VS 2005, available at the following link: http://support.microsoft.com/?id=927872 The informal explanation I got is that they had a fixed size internal buffer for holding type names during compilation, and the more complex MPL code--not surprisingly--exceeded that fixed size. I don't know the nature of the fix, though. BTW and FWIW, I never got the error message when compiling in VS 2005 on a 64-bit machine. Hope this helps.