This seems to be an issue in the On-Line marketing module. Could you specifc what version exactly (including hotfix) are you using? It would help a lot. It seems your AppBase file isn't the most recent one, judging by the content of line 1593. If you're not running the latest hotfix I'd strongly suggest applying it.
Or disabling the On-Line marketing in the settings should help as well. But if want to leverage its functionality I suppose this is not an option.