Hello everyone. So, recently, I obtained a new graphics card. I had installed the drivers and disabled the drivers of my onboard graphics which I was using. Everything was fine, until I played a 720p video (not streaming, it was downloaded). The video would lag and was very choppy, however the sound played fine. I tried other videos and they all were the same. I tried playing with another player, but to no prevail. Actually, the 480p videos would also lag behind the sound, but to a less noticable effect. By lag, I mean that the graphics would get further and further behind the sound, as in the two werent playing at the same rate. My old onboard graphics would play them without any problems. Oh, and the graphics card was the ATI Radeon HD 4550. Does anyone have an idea of what's going on? And any suggestions on what to do? I would appreciate any help. Thanks.