Lag spikes

Hello

I have been running Napoplean on my laptop without problems since release. However, after installing Windows 7 something has happend. For the first ten minutes of play the game runs smooth as butter. Then at some point a five to ten second lag spike hits, giving me an fps of maybe 5, and then I play smooth for maybe two minutes and then it hits again.
I have tried different drivers for my nvidia graphic card and playing around with the game settings, but nothing works. I also tried to find someone with the same problem on this forum, but to no avail.

Since upgrading to Win 7, have you installed directx 9.0c, C++ 2005 SP1, and .Net4 manually?

Do you have your graphics settings in nvidia Control Panel set to application controlled?