My dell wont respond any programs. i have windows 7 and mcafee doesnt detect a virus when i scan.?

it is hard to run the scan as Mcafee wont respond if i do as much as move the mouse while it is scanning. it wont respond Google chrome or Minecraft or even the task bar. Also, when i login it says that Microsoft.NET framework v2. something wont load or something like that. it is brand new and i dont know what is wrong with it.