Dell Studio 1737 Laptop issues

Hello,
After about 5 minutes into after my laptop starts up, the screen will go a random color and have vertical lines going down it. The screen takes on whatever color is on the screen and I can't do anything but the computer is still running. For example one time I was on Skype, talking to some friends and boom, the screen went yellow and I could still hear them and they could still hear me. But after about a minute the call went out. So I know it isn't a connection problem between my laptop and screen. I have tried plugging in a external computer screen and it still does the same thing. My friend downloaded SpeedFan and it was saying that my CPU's were getting hotter than they were suppose to. The laptop has one fan and maybe that is why, it's an older laptop about 5 years old. It was custom made. This has been happening for a while. I have been told by people that its my drivers giving out because they are getting to hot and I've been told that it's a bad connection which I don't think it's a bad connection. Please help!