Extension conflicts were sometimes a common nuisance on Apple Macintosh computers running the classic Mac OS, especially System 7.
This is triggered by several factors such as carelessly programmed and malicious extensions that change or disrupt the way part of the system software works.
Many Macintosh users had hundreds of extensions running on their systems, all of varying age and quality.
[2] This tool was also accessible by opening the Extensions CDEV in the Control Panels found in the Apple menu.
[3] Extensions were only loaded at startup time, meaning that any attempted change required a reboot.