When you first upgrade to Office 2007, one of the small "gotchas" in opening an older Access database is utility.mda.

Most Microsoft Access databases created in Office 2000, XP, and 2003 open and run just fine in Office 2007. Best to leave them in their original "mdb" format and run them in "compatibility" mode. Though compatibility mode sounds shabby, its not and to be preferred unless you specifically plan to use Office 2007 features in an all-2007 environment.