Go to Start Menu -> Control Panel -> Sounds, Speech, and Audio Devices -> Sounds and Audio Devices -> Audio Tab -> Sound Playback Advanced -> Performance tab -> Hardware Acceleration and set it to either 0 or 1 (Emulation or Basic).
If the problem persists then you may need a different sound driver in order to get the game to run correctly.
If this happens then you need to update your nVidia drivers on your computer. Up-to-date drivers can be found on the nVidia website .
Search for a file called Profile.dat and under properties uncheck "Read-only".
Try using the "Z" key instead. The keyboard controls for the game are Z, X, A, S, Q, W and the directional keys.
Run DoConfig and uncheck the checkbox on the top-left labelled "Use Gamepad". Now click "OK".
Make sure you have talked to all of the Koron/Colon again (the Mimiga raised by Curly) and then talk to the puppy again.
This glitch can occur after viewing the map in the outer wall while playing the WiiWare release of Cave Story (this may be limited to the initial US release as the bug may be fixed in later releases). To solve this problem refrain from using the map while you are climbing the outer wall.
Right-click on Doukutsu.exe, select properties, click on the "Compatibility" tab, tick "Run in 640x480 resolution", and hit OK. Do not have this set if running the game in windowed mode.
Cave Story is a little less than tolerent of unicode folder names, so whatever folder you placed Cave Story in it is likely that either that folder or any of its parent folders may have a character or two that Cave Story disagrees with. When in doubt stick with standard ascii characters. The other cause for this error is if the data files can't be found. Check that a folder called "data" exists in your Cave Story folder, if it doesn't exist then you may need to download the game again.
If you are using the steam version then right-click or control-click on Cave Story+ in your library on the steam interface and select "properties". Click on "launch options", enter "-psn" (without the quotes), and click "ok".
If this still doesn't work then click on "Go" and then "Go to Folder..." from the top menu of Finder and enter "~/Library/Application Support/Steam/steamapps/common/Cave Story+" into the input box and click "ok". Right-click or control-click on the Cave Story+ application in this folder and select "Show Package Contents". Open "Contents" followed by "Frameworks". Delete the folder named "SDL.framework" and replace it with the folder with the same name from this zip file.
DRM Free Version (Humble Store, App Store, etc)
For any other version you need to move or copy the "Cave Story+" application to the root of Macintosh HD for it to work. To do this click on "Go" and then "Computer" in the top menu for Finder. Now open "Macintosh HD". Move or copy the Cave Story+ application to this folder.
If it still doesn't work then right-click or control-click on the Cave Story+ application and select "Show Package Contents". Open "Contents" and then "Frameworks". You should now see a folder named "SDL.framework", delete it and replace it with the same folder from this zip file.
Download this file and extract the contents to the same folder as Doukutsu.exe.