Gee - you made me curious about my Eclipse II. I never tried to use those buttons except the lower right-outside to change colors.
So, I called up WMP and put on a nice MP3 cut to play with. The left side buttons each have wto functions, a rocker switch left or right. The top left one is fast forward and fast back for media. The lower left one is Play, & p[ause to the left and Stop to the right.
The upper right button is the volume control. Rock left is down, rock right is up. The lower right button rock left is a speaker mute toggle, and rock right is color change.
They all work.
Have you tried a different USB port?