It looks as bug #14911.
Oscar, are you sure you don't have flashplugin?
Maybe some files were keept after the package was removed.
Look at directories:
/usr/lib/firefox/plugins/ and /usr/lib/mozilla/plugins/
for flashplayer.xpt and libflashplayer.so files.
Do you have 16bit display?
It looks as bug #14911. firefox/ plugins/ and /usr/lib/ mozilla/ plugins/
Oscar, are you sure you don't have flashplugin?
Maybe some files were keept after the package was removed.
Look at directories:
/usr/lib/
for flashplayer.xpt and libflashplayer.so files.
Do you have 16bit display?