Today I had a very strange problem with a .NET application that accesses a Microsoft Access database using OleDb Provider. The exception message was "unknown", so I was really confused.
I wasn't aware that the problem was related to database access until I tried to open a Microsoft Access database using Windows.
Well, after this introduction, let's see the solution:
This registers a Microsoft Access DLL in Windows Registry.
This problem occurred in Windows XP Media Center SP3 but I'm not sure if this problem is only related to this particular operating system.