I've been battling this problem for almost a month.
I have a VB 2010 application that connects to an Access 2003 Database on the server. I have tried to change the connection string from "4.0" to "12.0" - following EE suggestions, but now I just get the same error "Not Registered on This Machine" only referencing OLEDB.12.0 instead of OLEDB.4.0.
I have found some suggestions on other sites recommending that I download either "AccessDatabaseEngine.exe" or "AccessDatabaseEngine_64.exe" but I want to be sure that what I am doing is configuring the one Windows 7 machine to talk to the 32 bit Access 2003 mdb file, and NOT stepping on the mdb - which is also addressed by numerous users still on Windows XP boxes.
Any step by step assistance would be appreciated.