I have saved a map to one of my 5 online save slots. It loads fine if I try to load it from the load menu ingame, and it works fine if I use the link on the minecraft.net homepage to open it as well. However, if I try to open it from the World of Minecraft Select a Server window, Minecraft will come up, say Reading.. for a bit, and then just generate a new level. I can still load that level from the load menu after that, but unfortunately, that just disables hacks, which is precisely what I don't want to do with this level.

Not entirely sure what's going on here, seeing as it loads normally in pretty much all other situations, except for that one.

Level link is: http://minecraft.net/play.jsp?user=betasword&id=4

Hope that helps.