Well if you used the sudo qtparted in a console window I suggested above then I am out of ideas. I see you were originally talking about this for the next time that you install which you can do of course and if you want to share the media files between windows and linux then make the partition an extended one type FAT and both OS's will be able to write to it. When you install the linux you will have to make these partitions extended ones as well.

The problem is I dont want to lose my music in the process of the reinstall

Maybe I missed something here, but not sure why you want to resize '/' partition.
Thought you were just moving your music so you could reinstall.

Anyhoo, its not going to let you resize that partition at all if:

1. There is no free space on the upper side, so it can't be expanded.

2. The data on the partition takes up all the available blocks, so it can't be decreased.

In that case it will let you know that resizing is not an option-- by not letting you.


s.d.

...now the only other question is what you're using to play .ogg files in Windows, heh.