Same problem here, changing the settings doesn't help.
Processor: AMD Athlon(tm) 64 X2 Dual Core Processor 5200+, MMX, 3DNow (2 CPUs), ~2.6GHz
DirectX Version: DirectX 9.0c (4.09.0000.0904)
Operating System: Windows XP Professional (5.1, Build 2600) Service Pack 2 (2600.xpsp_sp2_rtm.040803-2158)
Card: NVIDIA GeForce 8600 GTS
I would have tried software mode but the EXE appears to be missing.

Same problem here, slowdown when entering the pratice room.
Tried disabling smooth shaded stream, setting directx instead of directx + shiny but nothing works.
It's sad to see that the game wasn't tested enough before selling it claiming that it now works on XP.
Core 2 Duo 8200 @2.66 Ghz
2Gb Ram
Geforce 7900 GTX
Windows XP SP3

That seems to have fixed it, graphics are a bit chunkier but the "gray radar" issue is gone and above all the choppiness and slowdowns.
I took a while for me to figure out what to do from reading LlamaFarmers (is that you Jeff?) post so...
1. Download MDK again.
2. When the installer has started click "options" and then tick "MDK (Sofftware)".
3. Once the game is installed launch it from the start menu, if you use the "launch now" button in the installer you'll get the hw version.
A tip. Go into the mouse options and disable the Y axis, having it on only makes Kurt skip back and forth.

Well software mode fixed it, Thanks for the help.

Didn't fix my slowdown at all. Game is unplayable as is. I want (preferably) to play the game or at least a refund.

Switching to software mode worked fine. Thanks for the information.

Installed the software version, but when I try to run it nothing happens. The HW version runs but I get the same problem people is getting on the practice room.
Edit: I reinstalled a new driver version for my video card (old SiS) and restarted the PC, now the software version works like a charm :) thanks.

Thanks, that fixed it for me.

I have the same problem. I'll try this out, thank you!

Turning shaded stream off works beautifully!
Thank you ^ .^