We have found a problem with the plugins paths in Max 9/2008. In previous releases the paths were configured globally, but from Max 9 this configuration is local to the user.
The entry '<maxdir>\plugins', where Forest is installed, exists by default in the local 'plugin.ini' file. But if this entry is deleted, the plugins won't load.
In Forest 3, we have modified the installer to add this path to the file '<maxdir>\plugin.ini'. This ini defines what plugins are loaded for all users, so it won't be affected by the plugin configuration of each user.