You could try changing the channel used for the wireless connection. It is probably on the default "11" so try changing to something like 8 or 6.
Also ensure there are no cordless/mobile phones close to either of the wireless adapters.
Another option is to give the "client" computer in the ICS arrangement a fixed IP address, rather than getting it by DHCP from the "host". Sometimes ICS doesn't like you doing this, so it's a matter of trying it to see. Use these settings in the "client" PC:
IP address - 192.168.0.2
Subnet mask - 255.255.255.0
Default Gateway - 192.168.0.1 (the "host" PC's IP address)
DNS Server address - 192.168.0.1 (the "host" PC's IP address)