Quote:

The exact same thing just happened to me on all the song that I used the SAVE+ The yellow warning message says the program can't find the location of the realtrack folder. But it finds it fine for any new piece or for an older song that I just saved normally.



I may have found one (but not the only) likely cause of this problem: the SAVE+ button. It has no business being there at all in the latest versions. According to the 2010.5 PDF manual (p.182):

By default all settings are saved with songs unless the “Save all Settings with Songs” box is unchecked (off) in the Assign Instruments and Harmonies to Song dialog (Alt+F2 or File | Save Song with Patches & Harmony). This includes RealTracks, RealDrums, and RealTracks solos as well as Patches, Volume, Audio and MIDI Reverb, Tone, Panning, Bank, Harmony (both Melody and Thru), and the Soloist. If you have some custom items that you don’t want to save with the song you can uncheck the “Save all Settings” box and use this dialog to save only the settings you want to keep.

Now here's where we (or at least I) can easily screw up when pressing the SAVE+ button when using RealTracks.
When looking at all the check marks on the left side of the Assign Instruments and Harmonies to Song dialog it is VERY tempting to uncheck all those boxes next to all those irrelevant looking MIDI patches. DON'T!
Apparently that severs the connection to the RealTracks in your song.

I did say that this is not the only cause of the file-corruption problem, but I'll get to that later, after I have time for more verification.