Tarnum;
This quest is not broken in the download version. It is possible to have an issue completing it, just like it is possible in the disk version (even when updated).
Divil;
Did you refuse to get George the Drudanae herb at the start of the game? At least in the unpatched disk version that would break the murder quest, even if you later brought him his fix. The disk patch notes only specifically mention a fix for reporting the murder after Mardaneus leaves Aleroth, so I'm not sure if the problem of refusing George's request was fixed (if it was, it may or may not be fixed in the download version).