When I registered dao350.dll with regsvr32 and tried opening Visual Basic, it gave me an error: "Unexpected error; quitting"<BR><BR>I don't have the original installation disks, so I can't reinstall.

You probably need to declare area() as PASCAL calling convention and with the EXPORT macro so that it is, indeed, exported from your DLL. You'll also have to defeat C++ "name-mangling", so define it ...