What would help me with similar problems is an understanding of what the refresh in the media player is trying to do.

Does anybody know enough to give a blow-by-blow of what the media player is doing when it decides to refresh the media?

IF we could get a handle on that, we could think through why different things are happening and when certain steps are needed.

For example:
When does the media player decide it needs to re-scan the cache?
Daily?
when media player starts?
when M900 is turned on?

And then:
Once media player starts indexing, what steps does it follow?
Does it index by file names or by id3 tags?
Where does it look and which variables tell it to include/exclude a path?
Where are those files (that contain the variables) located?

If we had a description of what actually happens, we could figure out what steps are needed to fix different problems people have...