A drop down list with only one value seems very unusual. I'd probably set up that field with a check box format instead so that I can just click the field to clear or set the field to yes.
You can write your OnRecordCommit script like this:
If [ Not $$TriggersOff ]
Set field [ Yourtable::Qb ; "" ]
Then the OnObjectModifyTrigger on your QB field might perform this script:
Set Variable [$$TriggersOff ; value: True ]
Set Variable [$$TriggersOff ; value: False ]
If you "wrap" all trigger performed scripts in this type of IF block, all referencing the same global variable ($$TriggersOff), you can set this variable to True in any script where you need to be sure not to trip any other script triggers so long as you set it back to False before the script exits.
Thank you Phil!
It worked like a charm.