Can’t access my network using a cable

I use windows XP in my laptop’s, and I use a licensed copy of an Antivirus.
Everything works ok. In our office all laptops and computers get IP address from DHCP server.
I have LAN connection both cable and wireless.
When I use a wireless connection in my laptop there is no problem, but when I connect my network by cable connection, I can’t access others computer.
When I use a wireless connection it works.
It shows an error message that you have no rights to access local network.
This time when cable connection I can access internet. So what’s the problem?
