Hi BoogieBac, thanks for the quick reply and trying to help me!
Unfortunately rebooting did not help. 
I am running the game under Windows XP Home Edition (German version) with all the service packs installed.
Do you have any other ideas on how to solve the issue? Also, I think that I am not the only person with this problem, I think someone in the beta forums complained about "choppy fonts" as well, and the provided screenshots looked more or less like my screen.