Streaming on refurbed studio 15

Hi there,

I was just wondering if anyone could help me with a problem I'm having with my new refurbished laptop. Basically sometimes when streaming tv programes from the internet the screen will go blank and the laptop will be completely unresponsive, even ctrl,alt, del wont work so I have to push the power button to restart. It seems to happen more often than not when the programe is paused for a short period of time. I've tried to phone dell tech support and they were extremely unhelpful and actually pretty rude. The only things I could think of was installing divx and the latest version of flash. I've also increased power saving mode and screensaver so its not that. Can anyone suggest anything else as im not all that good with computers and its still happening. Its starting to freak me out as I don't know it there is something still wrong with it as it is refurbished. Any help would be extremely appreciated!

Thanks,

Lawrence