Here's a weird one..2k2/puter/helo's

Suddenly and unknown "how", none of my helo's (5-6) have rotors when flying. They're in the texture files ok..but somehow not translated to the screen. I think possibly, whatever spins that texture has "gone south". (it works ok with airplanes). Also, while they show flying at, say 90..they are barely moving....as if the "forward" effect has also dropped out. Any ideas on how to get it back? A file from the CD to merely re-write?