To run Maple Story under Windows 7, open
Right click MapleStory.exe and choose to create a shortcut (It should say GameLauncher - Shortcut)
Right click the shortcut you just created and choose Properties
Target line should say "C:NexonMapleStoryGameLauncher.exe"
Change the target line to "C:NexonMapleStoryMapleStory.exe GameLaunching"
Run as administrator.
Right click "Gamelauncher" and head to the compatibility tab
Under "Privilege level" check "Run this program as an adminstrator"
Or, if your lazy, right click on "Gamelauncher" > "Run as adminstrator."
Changing compatibility mode.
Right click "Gamelauncher" and head to the compatibility tab.
Under "Compatibility mode" change to Windows XP Service Pack 3 (Usually works)
If not, right click "Gamelauncher" and "Troubleshoot compatibility"