When I start up Skyrim and I'm at the main menu I start to get a lot of lag where my cursor moves slowly and jaggedly. This lag does not leave and seems to get worse if I manage to hit "Continue." I've made it in game once, but the lag was so awful in game that I had to quit. Although while I was in game I hit escape and that menu seemed fine and without lag, but returning back into the game the lag was still there. I recently played Skyrim (3 hours ago) and didn't change anything from then to now.
Things I've tried:

• Disabling Skyrim Script Extender
  
• Moving my saves from my documents folder to temporarily on my desktop
  
• Verifying the integrity of the cache via Steam
  
• Defragmenting via Steam
  
• Restarting Steam
  
• Turning off mods

I use the Skyrim High Resolution DLC and I have Dawnguard.
My specifications:
Microsoft Windows 7 Home Premium 64 bit,
AMD Phenom™ II x6 1045T Processor, 2700 Mhz, 6 Cores,
NVIDIA GeForce GTX 460, 8 GB Ram