Wireless hosts do not return ping

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DHCP operates on the adsl modem router with a pool from 192.168.0.71 (to 90) and a static table based on NIC addresses for all my common PCs in the LAN. This is working correctly. For example, my wired desktop gets 192.168.0.1, my ancient wireless laptop 192.168.0.50, the new wireless netbook 192.168.0.55, my dad's downstairs's wireless laptop 192.168.0.51 and so on. Wired and wireless hosts get the DHCP response every time.
The access point and the router are correctly configured to the network, wired to the switch and return pings correctly.

Yes you are correct. The wired hosts can not ping or ssh the wireless ones. The opposite is working. No firewalling inside the LAN. iptables -L confirm this.

The weird thing is that when the ancient laptop was operating Slackware 12.2 and ndiswrapper was used, I could ping and ssh it. Now that it runs Slackware 13.1 and native linux wireless modules and WEXT , it can be pinged some very very rare times. The netbook can never be pinged operating either Slackware 31.1 or its Windows 7 (firewall off). I kept Windows to do some checking of this kind.