Falling through the floor and unchanging maps

[Mudbill]

You rotate the view with Alt-M1. Alt-M2 zooms, and Alt-M3 pans. Scroll wheel also zooms.

There's a check box on planes which says "Collides". Make sure that is checked.

If map changes don't show, it might be caused by a cache file in your maps folder. Check and delete any .map_cache files you find.

If these are actual bugs, perhaps you should try reinstalling the game in case something messed it up.