I am experiencing the problem detailed in MS KB article 875300, the proposed fix of which is to rerun Forest Prep. Quick question (I hope!)... am I OK to run this during the day in a live environment? It's very rare that I get an opportunity for downtime, and I am conscious that while inconvenient, the problem I have isn't preventing me from doing anything I need to at the moment. If i'm better to wait, and plan for this during a downtime period then I will. Has anyone experienced any problems when rerunning Forest Prep? Thanks, Kelvin.

You can run forestprep anytime, and users should not notice any impact. Perhaps some additional AD replication (especially across site links) but nothing you need to schedule downtime for.