Hi there,
I had been having a problem in both Word & Outlook 2003 SP2, with folders in dialog boxes showing as "Music" Folders when those folder properties have been set as "Documents (for any file type)". This happens on when in detail view when attaching a file attachment using "Insert file" in Outlook, and on "Insert Picture" in Word. Not being able to sort by date with this view was quite frustrating if you are trying to select from a large number of files.
However, I have found a very easy fix that I thought I would share. I hovered the mouse cursor over the column headers in the dialog box itself, right clicked and selected from the column list "Date Modified", and unticked all those items relating to music files. I closed the dialog box using the top left x, & closed Word. The next time I went into Word my dialog box changes were still there. Interestingly, changing the "Insert Picture" dialog box layout in Word also changed Outlook's attachment "Insert File" dialog box.

Hope that helps someone!