Window Mode

I have problems switching Maple Story from full screen to window mode. Everytime i try to (alt+enter) or to (esc>system w/e> tick windowed mode) all i get is a beep sound. Ive disabled sticky keys, tried to open MS as admin or as XP program. Nothing works.

Also when i try to jump (which is set on my alt button) while im walking it wont work until i let the arrow button go, only then my chara will jump

Any suggestions?

PS. bought a new comp few days ago, Vista