Version:           svn 576968 (using KDE KDE 3.5.4)
Installed from:    Slackware Packages
OS:                Linux

ok, you're gonna like this (if you will be able to reproduce :) )
lately we got several reports on irc from people who claimed that sending global shortcut to amarok while it was crashing or something can tie up keyboard. we dismissed these, as some of them were running other window managers.
now, i had the same problem, running kde, so i decided to try reproducing the problem.

my scenario :

enable a dynamic playlist (i had a custom one), start playing a song. switch to 'files' tab, find some directory with lots of music (i had one inside my collection directory). when the song has some 4 or 5 seconds left, right click the directory, choose 'edit track proprties'. right after that, press a global shurtcut (i pressed win+c).

enjoy your keyboard. oh, did i say to save everything before trying this ? :>
the behaviour wasn't perfectly constant for me - sometimes amarok crashed shortly thereafter, freeing the keyboard, in some cases it just kept on playing (it played several tracks - i think 3 of them - and then whole system crashed. i got two small green consoles with kdm login screen below them...).
because it takes quite some time to recover in some occasions, i did not test this as extensively as i'd like to - but i hope it can be reproduced by others and that backtrace could help at least a bit. backtrace was obtained in one case when amarok crashed shortly thereafter, thus freeing the keyboard and leaving kde/x in a usable state.