Hello. I have managed to compile the SVN version of PythonDotNet against the 4.0 version of the .NET library with Visual Studio 2010 on Windows 7. I copied over clr.pyd, Python.Runtime.dll as well as new versions of python.exe and pythonw.exe into my C:\Python26 directory. I am now able to import .NET 4.0 modules after writing "import clr" :-) However, I have run into a few problems because I had to replace my Python executable. I am using a lot of packages from the PythonXY that depend on c extension modules (.pyd-files). Whenever I try to import such a module, I get the following error: Runtime Error! Program: C:\Python26\Python.exe R6034 An application has made an attempt to load the C runtime library incorrectly. Please contact the application's support team for more information. I think the reason for this is that I have compiled Python.exe with Visual Studio 2010, whereas the extension modules are compiled with Visual Studio 2008 (i.e. my Python.exe is linked against msvcrt10.dll while the extension modules are linked against msvcrt90.dll) Is there any way I can prevent this error from happening without having to recompile all the extension modules in my PythonXY distribution? The other solution would be to keep my original "Python.exe" file, but if I do that I get the following error message when I try to import the CLR module: In [1]: import clr ------------------------------------------------------------ Traceback (most recent call last): File "<ipython console>", line 1, in <module> SystemError: dynamic module not initialized properly Is there any way around this? Cheers, --- Øystein Skotheim Research Scientist, Optical Measurement Systems and Data Analysis SINTEF ICT, Trondheim, Norway