Hey,

I started a galactical conquest, the destroyal of Alderaan. But everytime the Death Star is about to destroy Alderaan the game freezes (music is still playing) and I have to kill the game with the task manager. It doesn't matter if I do it while I fight against Ackbar's fleet or try it to do in the galaxy map. Did someone else experienced this?

hmmm....never really heard of this problem.
And your description is a bit vague.....
Loading screen, battle screen?
But one thing you could try (if you haven't already ;) ), did you try to start the game in a different language version?

Easiest way, make a bat-file, with the following line:
swfoc LANGUAGE=ENGLISH

In case you use English, replace with GERMAN

This will start SWOC in this specified language and can be changed any time ;)

ok, never heard this one.

You could try to get the xml files from moddb (IIRC) and try again. The GOG version has the MP-fix, which means that the single xml files aren't there.

Maybe this will help your problem as well. Although, as said before, never heard of this problem prior.

Especially the action-slot freeze.

One thing which might be there, a save game corruption. Only way to verify would be starting a new GC. If the savegamedefreezer would help in your case, not sure (if you want to check, search on moddb, yes sorry to lazy to search for it ;) )