A few months back I thought I was going to write a blog post about how to look for RID Pool depletion in environments. Then I got side tracked with something (probably finding out why Mad Men isn't on yet) and Ned Pyle wrote an awesome post that would of put anything I would have wrote to shame anyways.
If you haven't read it I recommend you stop what you are doing and read it! So now you see how important that is to manage. There is a new KB Hotfix I recommended highly reading through it and then going through the proper testing channels for your environment.
MS KB 2618669
Some key highlights directly from the KB
In certain rare circumstances, a domain controller may issue recurring requests for RIDs from the global RID pool every 30 seconds. If repetitive requests for RID pool updates are unchecked for a significant time, the global RID pool may experience too much consumption, and in extreme cases, may experience complete exhaustion of the global RID pool.
To prevent too much consumption of the global RID pool, we recommend that you take the following actions:
Mark "No Diving In the Shallow End Of The RID Pool" Morowczynski