Whats the MAC, it keeps saying it is OK?
This is an integrity check. When used with the correct password it can be used to verify that the file has not been corrupted. My PKCS #12 application (and NS/MSIE) currently uses the same password for integrity (MAC) and privacy (encryption) by default. If you use the two pass option you can set and input separate passwords: such files cannot be imported into current versions of MSIE or NS.