Issue w/2 monitors on nvidia - dragging garbles windows (+screenshots)

Hello,

I run 2 flatscreen monitors (both in native 1024x768, 32 BPP) in Dualview extended desktop mode, on an Nvidia 8600GT.... and I'm having a display problem.

If I drag a window from one monitor the another, the whole window is being drawn incorrectly on the screen, and becomes garbled. See:





I need to minimize and maximize the window and then it gets fixed.
This problem disappears when I restart the machine, but after a while of working, it starts happening again. I've installed the latest drivers... still happening.

Is this something about the video memory not being refreshed correctly? How to fix? any ideas would be appreciated...

Here are the specs of the machine if this helps;
CPU - Intel Q6600 @ 2.40GHz
RAM - 2 gb
OS - WinXP Pro SP3
GPU - nvidia 8600gt w/512 mb, latest drivers

Thanks.