Via: Adobe Help Centre

Windows

Hard Disk\Documents and Settings\user\Local Settings\Application Data\Adobe\Adobe Flash CS3\language\Configuration\Classes.

NOTE

In Windows, the Application Data folder is hidden by default. To show hidden folders and files, select My Computer to open Windows Explorer, select Tools>Folder Options and then select the View tab. Under the View tab, select the Show hidden files and folders radio button.

Macintosh

Hard Disk/Users/user/Library/Application Support/Adobe/Adobe Flash CS3/language/Configuration/Classes.

NOTE

Do not delete the absolute global classpath. Flash uses this classpath to access built-in classes. If you accidentally delete this classpath, reinstate it by adding $(LocalData)/Classes as a new classpath.