Not just older boxes, but the Roku2 LT has limited storage space. ideally your channel should be around 500k or less if you wish to distribute to all platforms. Make your channel as small as possible by optimizing your graphics, off load anything that doesn't need to be in the package to your web server, and make sure no hidden / system files get zipped up (like thumbs.db and DS_Store) in your package. Also be sure not to zip up anything else that shouldn't be there, for example older builds of your channel, temp files, etc.
- Joel