When writing .NET code, always make sure the code is output as 32 bit only (i.e in x86 mode). 
This will allow .NET code to properly access 32 bit microscan dlls when running on Windows 7 64 bit or Windows Server 2008 R2 64 bit.

If the code is signed as "Any CPU", it will run  in 64 bit mode on 64 bit windows and be unable to access 32 bit dlls.

Visual Studio : Use configuration Manager to define a new Solution Platform as x86, and select that as the platform for building the project.

Affected program : MA5 Client (dated before 13 sep 2010), See MA5 Changes for Windows 7 Operation for changes.