The green light bug that occurs when using the R8BA024 firmware for the W580 after minimizing or exiting the Walkman can be "fixed." I've tested it out with my Citybeat flash theme and menu, and everytime I minimize or close the Walkman, the light goes back to the theme's colour, which is blue.
Hope it helps.
Edit: Only with the use of flash themes (Citybeat, etc) can "fix" the light bug.