I've got this issue with ATI driver version, 10.7, 10.8 and 10.8a. I'm not upgrading to 10.9 or 10.9a (I have an ATI4870 X2) because other users here report that the 10.9 driver does not solve these issues.
Come on TaleWorlds - help us out, using old drivers for warband means other games don't work as well that had fixes in more recent versions.
WIn 7 64 bit
ATI 4870 X2
ATI Driver 10.5