It's hard to answer questions when you give so little information about the computer...
Whenever posting questions on these forums, please give us as much information as possible about your computer. Depending on your issue, we might need the operating system, processor speed, amount of RAM installed, brand name of the computer, (if there is one), and any EXACT error messages you are receiving, and in your case, which media player are you using to stream the video. The more information you give us, the better informed our answer will be.
In the meantime, here's the shotgun approach:
If you haven't scanned the computer for spyware, please download, install, update, then run ALL of the free spyware removal tools from the links below: