Are there any problems in Device Manager? These will show up as exclamation marks.
Is the scroll/refresh problem any better in an alternative browser? Try Firefox click here & let us know.
What does a DirectX diagnostics test say on the Display tab click here (4th screenshot)? Are all the DirectX features enabled? Does it pass the 2 'tests' - DirectDraw & Direct3D? When these features are disabled/faulty I find my PC not quite running too well even in 2D tasks. G