Check that the firewall on PC3 has recognized the network and is allowing traffic through.
I have three computers connected wirelessly. All of those computers are members of the "HOUSE" workgroup. Having called the 1st computer "PC1", the 2nd one "PC2" and the 3rd one "PC3", I have the following senario:
PC1 and PC2 can communicate and share files with each other, while they can not browse to any shared folder on PC3. Even PC3 itself can not browse who's online in "HOUSE" workgroup despite I made sure it is a member of "HOUSE" workgroup by going to "My Computer" > "Properties" > "Computer Name" and check its workgroup name there.
Why - for example - PC2 can browse the "HOUSE" workgroup and that PC can not?
Note: The PCs run Win XP Pro.