While we don't know what exact specifications are for your computer, there are a lot of things that can cause this. If you are getting a lot of popup ads, something is wrong with that. How much memory RAM + paging file) does your system have? For streaming (audio or a/v), you should have a lot of physical ram because using your disk as memory (paging) can really slow things down. Your processor has to stop working on the streaming in order to swap programs in and out of ram. So, I would avoid running much else on your computer while you are listening to music. Yes, I know you want to be listening to the music while you work on a lot of other stuff. But try it out to see what happens. Also, you probably have an anti-virus product. You may want to consider putting in an exception with your security software for your streaming and see if that helps. What is your disk doing while you are streaming?
Streaming usually buffers to disk so you need to think about how much disk is available, how fragmented it is and how fast it is. Are you getting anything that tells you that you are short on "memory"? That can mean that your paging file can't expand. You may want to make the paging file a fixed value rather than letting windows manage it, especially if you don't have at least 40% of your disk free and unused.
Have you checked your event history after a freeze-up? There might be something in there that will help you. Are you just using the web for the streaming or are you running a player? There actually could be a combination of different factors that can affect this issue but please try to do only one thing at a time to narrow down the problem. Using the task manager while streaming can give you a hint where things go wrong. The performance information and the processes can be a hint. Unfortunately, there are a lot of things that can combine to make the situation happen as one can affect the other. So, other background jobs and grab onto resources needed by the streaming including ram/memory which could be tying up your disk drive.
You might want to find someone local to you that is good with performance issues that can take a look at this with you as we would need a lot of information just to start thinking about the problem remotely. Sorry, I can't be of much help.

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