Not sure what that problem is. However, I don't really know why you run it on both toons. I only have it running on my main, none of my slaves. I also use QuestAnnouncer to tell me the immediate quest status of my slaves(Jamba takes care of some of this too) and MonkeyQuest to list my quests and show me who has what quest (there are many quest add-ons for this, so I don't know if this is the best choice). I was also testing out JasonQuest recently which puts a window up that shows the quest progress of everyone in your group. I decided to remove it since I just have too much crap on my screen already and I didn't really find the additional information of much use.

Also, a lot of people prefer CarboniteQuest over QuestHelper. I didn't, but it doesn't seem to have the same resource issues. So, you could simply try that.

Cheers.