The snow in this map is retextured mud. Beam updates to make the game's mud... muddy. lol As a result, the "snow" acts like mud - you sink into it. You can fix it by opening the world editor, going to the paint panel, and just painting some RockyDirt/whatever onto that area. This map needs a lot of fixing, actually. Bad coordinates on every object in the entire map being the worst part. Another thing I'll have to set aside time for someday.