It could be a problem with shadows actually. Maybe the shadow min bias is too low or the mapsize is too big. I had a similliar problem and for the longest time I thought it was my morph that caused those weird lines, but it was a problem with the lights. Try using ray traced shadows or increase/decrease the shadow min bias.

-Morbo will now introduce the candidates - Puny Human Number One, Puny Human Number Two, and Morbo's good friend Richard Nixon.
-Life can be hilariously cruel