An UNPREDICTABLE EXCLUSIVE.
At least, I haven't seen it anywhere else, and I figured it out myself.
;-)
If you're in the middle of listening to a song in iTunes, don't select 'About iTunes' from the Apple menu. iTunes is iRude. It stops your music and puts up its own little Quicktime movie with visuals and sound that completely blows away whatever you were listening to.

To avoid the problem described above, DELETE the file 'iTunes Splash.mov' from your iTunes folder. This should be in your 'Applications (Mac OS 9)' folder (if you are at 9.1 or later, which you are, right?) SINCE there's no O&U column on Contextual Menus this issue, we'll make up for it by deleting the file with CM:
1) Open the iTunes folder.
2) [Ctrl] + Click on 'iTunes Splash.mov'
3) From the Contextual Menu, select 'Move to Trash'

'About iTunes' will still bring up it's window but it won't play the
movie, and this will free up 4+ Megabytes of drive space!!
:-)