It seems that this problem is not limited to Dimension. I have SampleTank2 and the SonicSynth2 plugs and there are some patches in there with these sorts of issues (not many, thankfully) and some drum patches in that grouping that you have to hold the key down to get the drum to play out its whole length - talk about useless!
I also found there are some REALLY bad loop points in the Garritan Personal Orchestra that came with Dimension a few versions back. It's in one of the cello patches. It makes the patch pretty much useless for several of the lower notes - too bad because, like that chorus patch, it's otherwise a pretty cool sound.