If this happened recently, then this may not help. But you can try extracting the update at this link to see if it helps. I have no issues currently and always use 100% opacity and high density. If you can hear the spells then it may be your SpellEffects folder missing the required image files. This can happen either by not allowing the merge or by having new SpellEffects folder in the original SpellEffects folder.
www.project1999.com/forums/showthread.php?t=128473