Problems with audio programs after update to Maverics

After updating to Mavericks on my Mac Mini there is problem with audio programs. I cant open iTunes at all, I click it and it disappear in a second. Also when I press play in GuitarPro 6 or in Vox player nothing happens. It just wont start playing. I really dont like this update.. and my mac is slower now. I cant downgrade my system back so this is really frustrating to me as a musician.