SevenSinner

i have the problem now when i get into singleplayer and hit e to open my inventory i get a screen saying something like closing down internal server and after that it closes my screen and opens the launcher again please help me

Whitelist application: IGN: SevenSinner Skype: danny.lampers Age: 22

1/name: Danny 2/IGN: SevenSinner 3/Age: 22 4/skype: danny.lampers 5/Have you been banned from a server: no 6/location: the Netherlands ( no thats not the nether ) 7/Nationality: Dutch 8/How long a day do you plan to play on the server: depending if i have to work or not if not i could play up to like 8 hours or more otherwise on a work day its around 2-3 hours 9/why do you want to be on this server: because its my first time playing with mods on a server and this look like a good server to start 10/hobbies: longboarding(distance skating and downhill) and playing my guitars 11/Any further questions?: no