I can't stop going forward after stop pressing "W"

Hey Guys, I'm wondering if it's a server's bug or it's something with my configuration. After stop pressing "W" my character still moving forward. I can't make it stop pressing "S" one time My charecter still quiet while i am pressing S but after a little start to going back. The most time i pressed W, the most time i still moving after stop pressing it. This is pretty anoying when i am walking and i stop to cast some spell. It's something like because of the lattency all the times I pressed "W" are saved and make my character still moving afte
Does anyone have any idea to solve this problem?