Windows 7 Corrupted Preinstalled On Laptop

I got a Dell Inspiron N5050, Three weeks of use I started having allot of problems, I restored to factory, three weeks later, same problems came back but Five Times worse. I thought it was a thousand different things and I've found out now that. My issue is a Pre-Installed Corrupted version of Windows 7. Is there anything I can do, short of buying a new version of windows? I've checked for problems with hardware and software, it says there's none, I've tried anti-viruses [Mcafee], Spybot, System Mechanic, Malwarebytes, and all the windows and dell options, every time, everything comes up clean.

So I've no idea why I keep getting a Black Screen, why I sometimes Blue Screen, and why after a Black Screen sometimes it knocks my screen res down very low, or sometimes forces my laptop to zoom in 300%, When it black screens it disconnects my webcam, it sometimes disables my ability to connect to Web Pages, sometimes it disabled my internet, so I am dumbfounded, and after all that, I was told it was a Corrupted Version of Windows.