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).
Both will cause dynamic channel changes that some clients/drivers can't handle well. So under Configure->Services uncheck "Automatically adjust xx GHz channels using.." (choices of Background Scanning and ChannelFly)
Aggressive sleep behavior on the laptops could also be an issue. You might check if there's a difference when plugged in vs battery (and/or set to full-power modes)