Windows 7: Can't access network computers except through remote desktop

I have a toshiba laptop that has always had flaky ethernet networking. Now I can't access any network computers on my home network, but the other machines can access the laptop with no issues. I can't access any homegroup computers nor can I map any shares from a server on the network running server 2008. I always get a message about the computer not being accessible. I even get this message when trying to access the laptops network shares on the laptop. How can the machine I'm on be inaccessible? Stranger still, I can access any of the computers on my network through remote desktop from the laptop with no issues. I'm no noob, Ive got Windows 7, server 2008, & xp machines on the same network that I have no issues with sharing over network. By the way, the laptop is running Windows 7 ultimate 64bit, like 4 other machines on the network.