I have two machines at home, connected with cross-over cable, one of them is always on-line, the other gets the internet from it. While there are no problems with internet connection sharing, I cannot browse my main computer from the other one (vice versa is possible!). How to solve this? I've disconnected the firewalls!
If properly set, firewall can't cause a problem in file sharing. Most likely your file sharing isn't set up! Or there are no folders/drives on main machine that are selected for sharing? Find a File sharing wizard in Network connections, and run it - I think that will solve your problem.