Unfortunately, you've given us NO INFORMATION about your computer.. Laptop? Desktop? Operating system? Which version of Flash are you usin? Which media player is used when streaming video? Maintenance details?
Either way, because heat can cause such issues, please take the cover off the computer and use compressed air to clean out all the dust and junk from around the processor, heat sink, power supply, and all fans..
And in the meantime, please click on the link below to follow some basic cleanup steps which include scanning for malware and removing any unneeded startup programs and services:
Hope this helps.
Every time I stream a video or play a flash game my computer feezes up. No movement on the cursor, nothing happens when I Ctrl Alt Del. Nothing. I switch it off and when it comes back on all is fine. Like I say, it only hapopens when I'm doing something that uses more of whatever it is that computers use to stream stuff.
PS I'm a novice at computers.