Upgrading from amaroK 1.3.8 to 1.4.0 is seriously broken - it corrupts the user's collections.db (containing the list of all their media files, as well as statistics on how often they've been played - I suspect this'll annoy a lot of users). Specifically, it bodges the update such that none of the existing tables are upgraded, but all new tables are created and the versions are set to make it appear as though they have been upgraded. (This is currently non-recoverable, at least without manual manipulation of the db.) A fix is at http://svntalk.pwsp.net/project/amaroK/revision/541986, though this doesn't help users who've already been affected by the bug. Note that although this has otherwise similar symptoms to #133603, it is distinct as removing ~/.kde/share/apps/amarok fixes it (by deleting the mangled collections.db)
*** Bug 133701 has been marked as a duplicate of this bug. ***
amaroK 1.4.0a in tree should fix the issue, sorry for the delay.