This has happened a couple times in my current project so far:
I'll have a composition in which a few (vector) layers use the "Write-On" effect. I then nest that composition in another composition. When Conintually rasterize is not set on the nested comp, it plays fine (although the quality is of course not quite perfect). When the switch IS set, however, the quality improves but suddenly the Write-On effects get completely screwed up. Basically only a few layers appear at all (when they should all appear) and the effect doesn't even reach completion.
Obviously the rasterize switch has nothing to do with individual layer effects (or, at least, it shouldn't). I also don't have any room to compromise on quality here; all vector layers must be perfectly sharp, period.
I've been trying to work around this problem so far, but I'm out of room there. I need to get this solved. Does anyone have any idea what's going on?