40D Tv malfunctioning?

My 40D is not able to set the shutter speed right in the Tv mode. I did some evening indoor tests w/o flash. For example, if I set the shutter speed to 1/200, the camera will reset it to 03 whenever I half-press the shutter to focus. The Av mode works fine though. Has anybody gotten into the same Tv problem? Or is there some setting that I don\'t know? Thanks.