Another Wierd Problem

I have made some more progress in setting up the CEGUI. Right now I am able to use scheme to show up a window, and tried out CEGUI's utilities.
But now I encounter a very weird problem, which is still under investigation. It appears that after drawing CEGUI windows, my texture coordinate of sprite is messed up. It's kind of wierd because the model's texture is still correct. I think CEGUI must have change something in the directX device.
I think I might have encounter similar problem before, but not sure. In any case, further investigation is required.