Opening Access files over a network

I am running XP and have a working wireless network. I can successfully open files to all my Microsoft Office programs such as Word and Excel. However, when I try to open an Access file over the network I get a message saying “This file is located outside your intranet and won’t open it for security reasons.” Of course I have my Access files in a shared folder on my main computer. Even if I move Access files into a shared Excel folder I still cannot open them, even though Excel files work OK. It seems there is something special about the Access files that denies me access (no pun intended!) Help please!