Weird graphics in 2002

I just got a geforce 5700 ultra and now there are some very strange things happening in FS 2002. First, I should say I've downloaded all the latest drivers, for the card, the chipset, the motherboard, etc. It's an athlon 1.3 with 1 gig or ram.
When the game loads, I get framerates in the twenties at first, but almost immediately, it slows down to 5 or 6 fps. If I alt+tab out of the program and back in, the frame rates go back up, but the 3d objects in the game get all screwed up. Buildings that are the furthest away show up in front of the ones closest to you, you can see things like wing struts inside the plane. It's like the order of objects from front to back is backwards. You can alt+tab again and the craphics go back to normal, but the frame rates drops to 5 again. I have looked everywhere for an answer to this. None of the graphics card forums or newsgroups can help, microsoft has nothing about it on their site, there are no patches I'm aware of.
I formatted my hard drive and reinstalled windows XP, SP1 and all the drivers and then the game and it still is happening. There is nothing else running at the time. I just don't know what else to do. As far as I can tell, the card works fine with other programs (though it's not as great as I had hoped).
Any ideas?

May I ask what who is the manufacturer of your 5700 - what varient? What AGPX speed slot are you running it in?

It's an eVGA GeForce 5700 Ultra, using nVidia drivers 53.03, and it's at 2X, because I can't seem to get the system stable at 4X

I very recently applied new Geforce drivers for my machine (Geforce 4 mx) and I have today ontcied the weird overlaying issue you mention. Wonder if its the latest Geforce drivers?