The perspectives and thoughts shared above are extremely important in keeping a forum healthy and members happy, but I'll mention some issues from more of a marketing point of view. [Yea, I know that sounds dull!]

Some things I have seen on other forums (not PC) that contributed to their downfalls:

* Allowing too much focus on a small number of members

* When interesting new threads stop or slow being posted and only one or two threads are active

* When new members are not welcomed sufficiently and given attention

* When the topic of the forum is strayed away from too much/too often in ways not at all relevant to the forum purpose. This is important!

* In the case of a bipolar forum, when too many people who are "friends", "family", "spouses", or "girl/boy friends" post too often, unless the forum is specifically for them. Or when too many people without an official diagnosis become very active in the forum. The whole "Will you confirm my self diagnosis?" thing.

* When there are too few supporters in comparison to people who are desperate for support

* When the forum leans predominantly in one direction in a significant way (e.g. if 85% of members have bipolar type 2 vs. some other form of bipolar OR, almost all members are female with few/no males).

* When aggression is unchecked by moderators.

* When members refuse to forgive others in cases where forgiveness is reasonable. Some people with bipolar disorder do indeed sometimes have symptoms that are unpleasant to others. One can't expect the same standard of conduct from others, when symptomatic, as one expects from themselves.

* When a forum's Terms & Conditions are excessively strict or excessively lax.

* If the ease of navigation (and finding things) of a website decreases.