Whenever I use certain applications, I see the following error message:
"The application<application name> has unexpectedly quit, because an update to this software is required for compatibility with the improved Mac OS file system.
"You should save your work in other open applications and restart the computer.
"You should contact the developer of the software that quit to see if an update to ensure compatibility with Mac OS 9 is available."

In order to modernize the Mac OS's foundations, Apple greatly increased the number of files that can be open from 348 in Mac OS 8 to 8169 in Mac OS 9. The total number of open files includes many files used by the system, such as fonts, and files used by applications, such as documents, and so forth.

This change means that you can install many more fonts and other system resources without running into the 348 open file limit. Unfortunately, it also means that some programs that relied on an outdated method to access the system will fail to work.

Any program could be prone to encounter this error, but for the most part, applications that worked in Mac OS 8 but that won't work in Mac OS 9 fall into the following categories:

• disk utilities
• file compression
• font management
• virus utilities