Win7 Laptop SLOW, occasional buzzing sound, bluescreen

Hello experts, recently I found that my computer running Win7 Home Premium is becoming slower. And the annoying thing is that, when my computer plays music or video, the audio occasionally becomes the BUZZ sound, with the discrete "jumping" of mouse cursor if it's moving.
Once when the issue was bad, a Bluescreen occured with an infinitely repeating noise (buzzing again and again), and the screenshot of the Bluescreen is uploaded.

Some specs:
Windows 7 Home Premium on Laptop Dell V130
2G RAM, (usually 85% is used);
CPU: i3 @ 1.30GHz
Processes: 81 (as currently - too many?)
Services started: ~80

Could anyone help me find out the problem and solve it? Thanks a looooot!