How are you building the application? As AnyCPU, x86, x64, etc? Also, have you installed the x64 version of the VC++ Runtime? Starting with VS 2010 there are separate versions of that runtime.

I -think- it was due to the Platform being 'Mixed Platform'. I altered this to 'Any CPU' and it seems to do the trick, however it also seems to have broken Visual Studio a bit - 'Build' > 'Rebuild' has no effect, but right-clicking a project and 'Rebuild' does..!

I can live with that though. Hopefully the Platform setting was the problem - I'm going to test it on some more machines to find out.

Thanks again.

The project is probably not set to build in that configuration. Open up the configuration manager and make sure the project is checked off as being included.