Important information about Mac OS 7.6.1 Update for customers using non-U.S. English systems "U.S. Mac OS 7.6.1 Update" and "U.S. Mac OS 7.6.1 Update for PowerBook 3400" should only be installed on systems running the U.S. English version of system software. Installing these updates on computers with system software localized in languages other than U.S. English is not supported by Apple and can result in system instability. Customers with system software localized in languages other than U.S. English should wait to install localized versions of the update, which Apple expects to make available within 90 days of the U.S. English release.