There can be a few solutions to the problem. One of them is knowing how to use the File exchange control panel. For new types of files you need to add them & then add which app(s) should open them. One of the issues is a problem with pre-OSX OS LW dwnld files could lose their identity. For stuffit files that have a white icon, drag & drop is the best way to open them. It can depend on the file type as to what's the best temporary solution for using them. WMP might help solve some of these identity issues but guaranteed not to solve all of them for all file types.