Ok, I found a solution for the problem of the scan bar for music... you need to do a soft reset... Not a reset by removing your battery, but a reset like you do when you uninstall a software. After the reboot the scan seems to be good (worked for me 3-4 times...). If you don't able to reset, use software like SoftReset.

Btw, is it me or the phone seems to be slower with 4.5? And more slower when you listen music with bluetooth stereo headset?

Thx