This article discusses difficulty installing Macintosh System 7.5 on a Performa computer. You may receive a generic error message saying it cannot install System 7.5 on the hard drive.

This may be a folder lock conflict.

Prior to System 7.5, the Macintosh Performa computers used a slightly modified version of System 7.x, including the Performa Control Panel. It provides folder protection by locking the folder so items cannot be accidentally removed. Only the System folder and the Application folder can be locked using the Performa control panel.

Before you can install System 7.5, turn off System folder protection in the Performa control panel. Under System 7.5, you can turn System and application folder protection off and on using the General control panel.