Blue screen? This is my dad's computer's specialty. Record is 4 times in 5 minutes...
Ok anyway:
- Heat - The main reason that this computer BSOD'd... Check your fans over the graphics card, processor and the case fan.
- Virus - Possible way that it's told your pc to crash or BS.
- Overclocking. I once made my PC BSOD when I opened up heaps of the same movie - it couldn't handle it and gave up.
Not entirely sure about the network problem, but slow browser paging could come from a not good enough processor or something like that.
Again, just check all your fans and give your PC a good virus check.