My display driver stops when i plug in my HDM

hi i have a toshiba L500 and im trying to connect it to my LCD tv. my laptop and my tv both have HDMI ports and i have tried to link them together. iv heard that u have to plug the tv in first then start the laptop i tried this and it worked while windows was starting up but then as soon as windows has started up my tv screen goes blank and my laptops screens starts cutting in and out of blackness then when u unplug the HDMI cable it all goes back to normal but it says my display driver stopped working but has recovered.
what do i need to do to stop this do i need to instal a new graphics card????