We had our first run against DT yesterday. We downed him and didn't run into any buff/debuff issues. Our tank pulled, we ran around behind DT and went from there. As we didn't really know what we were doing we were expecting the white circle to do something so this vid shows some hilarity but also that we had no issues:
Dreadtooth Successful Run
Ah, good to know/see.
Even if we basically did nearly anything the same way you did and I still have no clue what caused the debuff... it's really good to see that it "works".
I'll have my guild/friends-OP start on the same spot (unstimed, unflaged etc.) and try to narrow it down from there.