I just got back from somewhere, anyways... I actually had problems with Microsoft.Jet.OLEDB.4.0 especially in a 64 bit machine. This is because Microsoft.Jet.OLEDB.4.0 is designed as a 32 bit component. If you compile your solution as AnyCpu, it shouldn't work since an x64 process cannot load x86 component. So you have 2 options.
1) Change the compiling to 32 bit mode.
2) Use Microsoft.ACE.OLEDB.12.0 provider instead of Microsoft.Jet.OLEDB.4.0. This uses .accdb instead of .mdb. This is more future proof since the last time I heard, 2003 office won't be supported anymore :)