Ian,
A couple of questions sprang to mind as I read through the thread ...
1. You say that "files seem to open but not correctly". How do you open them and in what way don't they open correctly?
2. With the songs you've been creating, have they been complex in that there are multiple changes of instruments and drums within the song?
3. What is your audio set-up?
4. Have you tried "Opt | Preferences" and then (re)setting the path for the Realdrums and Realtracks?
To set the paths, once you're in Preferences, simply click on Realdrums and then select the "use a custom location" option (#1). When this is selected, a folder (#2) will appear. Click on this an navigate to the location of the Realdrums folder. Once that's done, click on the "Realtracks" option in Preferences and follow the same process.

Regards,
Noel