I have a music folder with 228 objects in it (mainly subfolders, but some 
mp3's at this root level too).

I use the Fishbone Skin (although I have tested the following with the Default 
skin too).

When browsing this music folder, sorted by filename, there are first-letter 
navigation links at the top of the panel.  I have duplicate links for "1" 
and "(".  The links line looks like:

 |  1 ( 1 ( 2 A B C D E F G H I J K L M N O P R S T U V W

I have a few mp3 files that have the track number at the start of the 
filename, and a few folders that have the year of recording at the start of 
the folder name (sometimes in brackets).

I have files beginning with digits other than 0, for which there is no first-
letter link (eg. "05 Circles of life.mp3").

It appears that the items are correctly sorted alphabetically (if leading 
bracket characters are ignored).  If leading brackets are ignored for sorting, 
then perhaps a bracket should not appear in the first-letter links.

Incidentally, it might be better (add a prefs option perhaps) if all 
subfolders were to be listed first, then any music files within the current 
folder.