Many developers switched to Windows 7 64-bits. If you are one of those and still have to use the Jet engine to access some data, you surely had a problem and you probably changed your targeted platform in Visual Studio to X86 because it is the easiest work-around.

But do you know that 64-bits drivers are available? It is available from Microsoft Access Database Engine 2010 Redistributable (a version is also available for Access 2007).