Need For Speed Shift: Weird stutter

[FuzzButt]

My system specs are in my profile.

The game runs perfectly on Windows XP 32-bit. But when I play it on Windows 7 64-bit, I get this weird rhythmic stutter.

It's very similar to what happened to this user on the game Race Driver GRID:
Weird Slowdown problem - Codemasters Forums

I have that game too but I don't have that problem. Instead I have the problem on NFS Shift. Basically its that slow down but it happens faster and in a rhythmic pattern. Not really a framerate drop but similar to a microstutter.

I tried what was suggested on that forum. Here's what I've also tried:

Compatibility mode in Xp SP3, Vista, Vista SP1, Vista SP2.
Disabling visual themes and such
Updating audio and video drivers
Reinstalling the game
Lowering the graphics settings

So any help?

 

[Frostmourne]

Did you clean install 7 or upgrade?

 

[FuzzButt]

Did you clean install 7 or upgrade?

Clean install. Well I made seperate partition for 7 as you can't upgrade from XP to 7.