>Anyway, I restarted my PC and going to re-try. If it would not work, I have other things to work on, I would put this particular page aside for the time being - I'm already quite depressed with it not working for no apparent reason.

Well, the key question is usually, "What changed?" - I tend to rely on source control to help me answer that, since you tend to forget some of the small changes. I've also occasionally had to first do a "Clean Solution" then a full rebuild to fix some odd errors.