Here's a nice one. Before experimenting, I had internet working on all wireless devices. Since that wasn't enough, I may have mucked up my internet connection.
I have several computers, two printers, an ADSL modem, and a wireless router plugged into a D-Link Gigabit switch. Internet was working on the wireless devices. All wireless devices could detect one another and share files. All wired devices had internet, could share files, and print.
But the wired machines could not detect the wireless router or any wireless clients. And vice-versa.
These wireless machines need to print to shared printers and access files on the shared drive (wired).
Since disabling dhcp server on the wireless router, and re-activating it, wireless computers can only access the router, and not the internet.
I would suggest:
Unplug everything, and shutdown all PC's then run this set up.
Turn on the modem first wait 2 minutes, then the router wait two minutes, then the switch. Then fire up the PC's, and you should be good to go.
ADSL modem > WAN port of the wireless router > switch connected to the router (depending on your switch, you might need a "crossover cable"). Router hands out DHCP addresses, and I would suggest IP reservations since you might share out your printers ect...