Bugs:Mega Man Battle Network 4
This page details bugs of Mega Man Battle Network 4.
WoodMan Scenario Bug on Nintendo DS
During WoodMan's scenario in the second tournament, the game might slow down severely when played on an original Nintendo DS if a menu or battle is accessed in Park Area. This occurs on DS' hardware level because the game fails to check the need to reset animation frame reset index when Wood Towers are there, resulting in an attempt to load a non-existent sprite from an invalid memory address. The DS hardware treats this data as a continuous sprite data, resulting in the near-hang slowdown as the game attempts to wrap back to mapped, valid memory.
Nintendo acknowledged this bug on their website, although only Blue Moon is credited; the bug can also occur on Red Sun.