This should be a common combination (windows 8 w 9.4.3 APs), but in checking our case histories, etc I am not seeing pervasive reports of issues (only 1 iffy match). The fact that it's Windows 8 may be a red herring. For example, it may be 802.11h (channel fly) settings in the driver those laptops happen to be using.
Can you turn off ChannelFly temporarily and see if it helps? (set the channel manually).