decidedly average

Hi there, for a while ive been having issues with my laptop, ive got an acer aspire 5100, and ive had it for a few years so i probably need a new one but im a student and im afraid bills come before shiny new toys.. For a good few months, every so often when i am playing music on itunes or spotify my laptop will completely freeze and let out a continuous, loud, drone, and not turn off unless i remove the battery. This doesnt happen all the time, but the frequency is increasing, and its getting pretty bad- not to mention annoying! Also for the past few days i have noticed if i try to stream any video the picture freezes, then jumps, then freezes. I can momentarily solve the problem by pausing or restarting the video, but it always ends up doing the same. The audio is fine along side it, but the video is impossible to watch. Im wondering if its something to do with my sound/graphics card?? Although i had a whole new hardrive installed around 8 months ago, and the laptop has never really been back to normal.. I just dont know what i need to do to fix the problems?! Any help would be greatly appreciated!!, Thanks!