If a shared printer is on a computer running Windows XP SP2, make sure that the firewall is configured to allow access to the printer by remote computers. Use the following steps to view or change the firewall's settings:
1. Open the Properties dialog box for the network adapter.
2. Click the Advanced tab.
3. Click the Settings button.
4. Click the Exceptions tab.
5. Be sure a check mark appears in the File and Printer Sharing option.
Or, to create a full-blown wireless file sharing network with easy access straight from boot up, the following settings require changes:
1. Workgroups
2. Sharing Folders
3. Configuring Firewalls
4. Mapping Network Drives
5. Customized O/S's
Once changed, each PC can see each other's sharable folders. If you need further assistance with the above settings, and how to change them to create a network, let me know and I can reply with the proper procedures for doing so.
Otherwise, for further help fixing your network, here is a link to another thread post regarding a problem/solution to what appears to be a similar issue to the one you're having:
https://forums.macrumors.com/posts/5351718/
Hope this helps!