Internal Speaker Problem after "crash"

Hi, I was loading three videos at the same time with quicktime player last time on my macbook pro 5,1 (aluminium)
and those videos seem to have crashed the system... everything went really slow, then all of a sudden the speaker sound (playing i-tunes) changed,...
since then, after restarting and shut down... the speakers seem to have a bass overload...
the sound is really horrible, and i can't listen to music anymore.
anyone an idea how to fix this problem?

my headphones work normal, the change only affected the internal mac speakers.

is there something to restore the audio function?

It sounds like maybe the internal speakers are blown somehow. If so, your only option would be to replace them. However, let's rule everything else out first. Is this only a problem with music, or with videos also? In Quicktime only, in iTunes only, or in all apps?

Check your EQ settings in iTunes, found in the "Window" menu, or by pressing the key combo: OPTION-COMMAND-2

i don't think i blew the speakers, as this problem was suddenly, and i wasn't really listening to loud music, i usually play heavy bass stuff which never affected my speakers, but at this moment i did not...

well the settings seem alright... and the sound is also like this when i use Skype or other things...
it could be a defect of the audio driver caused by the crash, but i got no idea how to fix that if it's possible?

i checked something, if i set the equalizer from 32 - 500 to lowest and from 1K + to middle, i get an OK sound, but can still hear the strange sound in the voice...

any advice??

does anyone have any idea how to get my speakers back to original state?
skype and other software still affected, as there's no equalizer...