Network Access One-way street

I have a Dimension 3000 desktop computer. I have set up a home network using a linksys router. It worked fine for over 6 months. The computer that I am having trouble with connects to the router using a wired connection from the NIC card. Dell checked out the hardware for the NIC card and it passed all tests. I tried replacing the wire but it was not bad. I have a green light at the source of the NIC card. The problem that I am having with the Home network is that I can see my two other computers on the network but when I try to gain access to the shared folders and printer it says that I do not have access and need to see the admistrator even though I have administrative rights. When I go onto my other two computers they see and can gain access to the shared files and printers on the problem computer. I have run network diagnostics on the home network and the linksys router and all tests were passed. I moved my wireless USB connector to this machine and then everything worked file, where it could see and get to the other computers on the network. The problem is with the wired connection to the home network, anyone have any ideas on this issue?