Jerky playback when vlc in full screen on laptop

[itsamee]

Hello, my movies played back with vlc in my tower pc work fine at full screen, however when I use my laptop the full screen is just jerky until I've found that decreasing the screen size cures it. This is not good for me as the ensuing picture is too small for me to read the subtitles (I'm a deaf person). How do I cure this problem please? Thanks
David