Ice demon damage over time effect sometimes doesn't work. It appears to be random. I tried this at multiple mobs and also tried clearing out mobs to see if it works when they respawn, but appears to be random anyway. Around 50% chance it will apply. Mobs it doesn't apply to will never get frozen by ice demon when I try using it again. It has always been 100% on all mobs this effect can apply on. I don't have F/P mage, but I'm going to guess it may be the same with fire demon.
Have you tried using windows 7 compatibility mode? I saw matt writing about it as a temporary fix in other thread.
Nope. It ain't a severe issue anyway, unless I'm at really high level mobs like Neo Tokyo or Shalion clones. Just wanted to report it so it gets resolved