So they're totally different level types. The dungeon is relatively lightweight for loading, while the open forests are big and have to load a lot.
First things to try would be update windows then update GPU drivers. I tend to find more often than not that issues resolve when everything is up to date. If it's not getting to the black loadscreen then it can't open the level at all. Does it do it for every forest level, or just that one in particular? Could be an unseen error in one of the levels.