Be sure that your Money (*.mny) and backup (*.mbf) files are copied
to a spot that you will have full privileges to, such as Documents.
If they are in a place like ProgramFiles, Windows 7 will create an
impermanent copy of the file for the user to use, unless the user
explicitly right-clicks at launch and choose RunAsAdministrator
that time.
If you upgrade from US Money 2003 or before to Money Plus, see
http://support.microsoft.com/kb/919524/en-us or
http://support.microsoft.com/kb/913108
You may want to consider moving to Money Plus Sunset while you can.
After you open your Money file, change the location to which Money
backs up to a location that exists on the new computer -- typically
your Documents folder or a sub-folder in Documents.