Why does my cycles preview cause my PC to freeze Whenever i switch to the rendered view my whole PC freezes every so many seconds is there something not right in blender or is my PC just not up to it anymore?
It seems like your CPU/GPU can't handle the cycles render.
Cycles samples the scene as fast as it can, I think your computer freezes while trying to sample the scene:
 (You can find this at the top of the 3D view.)
I suggest trying a simple scene and see if that stops freezing the scene. If it doesn't, I believe there is a problem with your CPU/GPU or it is not supported for Cycles.
It may just be a problem with selecting the wrong computing device. If you have a supported GPU you can select it like me under User Pref &gt; System:

And then selecting GPU under the rendering tab:

And if that still doesn't work, try selecting the CPU instead.
And if all that fails, I recommend getting a better GPU/CPU. You can compare and find the best one for your price here: http://olivieramrein.com/2012/02/25/blender-cycles-best-hardware-using-the-benchmark-spreadsheet-analysis/