Edit: I now see that the 74 upvotes that your question accrued have vanished.

But in any case at the end of a bounty if an answer with reasonable score exists there will be an automatic accept and awarding of part of the bounty points.

As indicated this is also in the FAQs http://mathoverflow.net/faq#bounty , though I believe a detail is not correct there, in that it says the answer needs to be given after the bounty was placed, but I know for a fact this is not so as I once got an automatic accept on an answer that was given before the bounty was placed. But I can confirm that a score of 1 is insufficient for an auto-accept because once I did not get an accept on such an answer.

Anyway, on SE1 there are/can be automatic accepts if there is a bounty.

Kerry, the user profile shows activity so I don't think that there is a split account, but there might still be (if you are using different computers). Please check your user profile and see whether or not the question appears under your user (the one where you can't see check marks).

(Personal note: Kerry, if I were you, I would just edit the question mentioning prominently that you would be still interested in a complete answer; I do not believe you loose much visibilty by there being an accepted answer. In any case your question would not be in the unanswered category, having upvoted answers, and since it is so highly voted I think you keep quite a bit of visibility anyway. The bump via this edit, would I think give you in the end more visibility then if there just were no accepted answer. That you cannot delete or undelete answers is not surprising; only moderators can. It is also normal that you cannot delete your questions; at this stage (independent of the accept) again only moderators could.)

1. Kerry succeeds in accepting a different answer, and I notice.
2. Kerry fails to accept a different answer, and posts about it here, and I notice.
3. 24 (or maybe 48) hours pass.
4. Some other moderator decides my experiment is silly.

If another answer is accepted, I would be interested to see what happens after Agol's answer is undeleted. I suppose in an ideal world, bounty assignment would be completely separated from the answer-accepting process.