I have had these same problems in empires and id DoD:S Mostly due to massive lags during loading & creating the map
http://forums.bsid-clan.com/index.php?/topic/71-texture-glitch Don't think you need to reg to see it.
Same thing happend to me in MW2 and was like wtf after the giant lagg and almost loosing connection i started seeing the throwing knife icon on the walls and Headshot icons on the airplane in afghan.... IDK why but i have a feeling its the grapichs card (strange feeling)