Help with warrior Marc?

You must install the game then the release patch 1.1 and then the 1.06 patch, in this order. here is the link: http://www.jowood.com/?lang=en&site=2&iid=Patches&gameid=gothic3_AO&pfid=PC If this doesn't help then load an older saved game. You might try do do the next quest Theodor gives you (without being given to): you must find all the artifacts between Ardea and Vengard. Speak with people in town to get the artifact. Those artifacts you can find in Reddock ( on the table where the Smith used to be, on Severin - left side of the Ardeea's gate when you teleport, you can buy the other one from some nuts guy in town.

After talking to Marc, return to Theodor. If you see no dialogue response to his question except END, click in the blank space above END and the game will continue.