I’ve noticed 2 problems with More Fields in one of my installations:
1. wysyiwyg boxes in More Fields metaboxes are tiny with no toolbars
2. all metaboxes on the edit page or edit post screen are “frozen”: can’t open them if they’re closed, can’t close them if they’re open, can’t drag them to another location.
Both of these problems were noted by others above. When More Fields is deactivated, the metaboxes are “unfrozen.” Of course, the More Fields metaboxes are then gone, so the wysiwyg problem in them is gone also.
What’s confusing is that I have other sites using WP 3.3 and MF 2.1, and not experiencing the same problems. So it’s possible there is a conflict with another plugin.