Ray Detail Multiplier controls the multiplier for certain raytraced elements vs. the main scene detail. 0.25 is the default, meaning underwater geometry, reflections, etc. are rendered at 25% (1/4) main scene detail. A value of 1 means they should be rendered with equal detail to the main scene. So a value of 100 is... insane.
If a value of 1 is not helping you, then there's something else wrong. I would never suggest using anything more than 2, and even that would be in extreme or unusual circumstances that I can't really think of right now (but probably there is some reasonable situation to do it, just not 100, hehe).
Anyway, it looks like it may be a bug. Can you possibly share the scene? You can send it to support AT
planetside.co.uk. There may also be other settings in the Subdiv Settings Node that could help, though I'm not real familiar with those options yet. Something like unchecking "Fully adaptive", for example (just a guess).
- Oshyan