Powers that Hold, Sleep, or Disorient will all turn off your toggles if they overcome your mez resistance.
Immobilize will only prevent you from moving, but will not affect your toggles.
Knockback will... well, knock you back. But it also will not affect your toggles.
There are some powers that have a small percentage chance to knock off a single toggle, such as Brawl. This is especially prevelent in PvP.
As Saturn_Knight said, sleep/hold/stun will drop your toggles. As for individual powers that have a chance of dropping one or more of them, here's a post by _Castle_ listing them:
Toggle Drop Post 1
Toggle Drop Post 2
I have seen abilities that turn my toggles off, is there an updated list of what all CC abilities are capable of doing?