I've recently gotten a new computer (approximately 1 and a half months ago) and I have been having problems with crashing/blue screens. I think it may have something to do with the video card, but it could really be anything as I'm not to computer savvy.

Problem description: Whenever I have alot of tabs open (alot meaning +12-13) on my browser (ie) and usually the tabs have either youtube videos or just a random slew of sites; my computer often freezes, and when it unfreezes I often here an awful sound (not sure if its from the speakers or the computer itself) and I get a blue screen, followed by a computer restart which freezes again at the loading screen causing me to have to hold the power button in and restart it manually.

On a side note I can no longer play starcraft, I recieved a notification on the bottom of my screen informing me that my graphics card was incompatible with the game, but up until a few days ago I had no troubles. When I try to log into SC anyways it says I cannot connect to the network and I should check my internet connection. I am normally connected with no problems, and am still allowed to play single player offline. If its my video card wouldnt it effect single player as well?

System Specs:

Dell XPS 8300
Windows 7
CPU: Intel i5 2500 at 3.3 Ghz
6.00 DDR3 SDRAM 1333Mhz-4 DIMMs
GPU: AMD Radeon HD 6450

My moniter is on max resolution if that matters, if I need to supply anymore information let me know and I'll try to be as detailed as possible.