This isnt FIRST related but it would be really cool if someone could help me

[cdennisxlx2]

I have an odd networking problem, hopefully someone here has seen this or something because i have never seen this like this before

Ok I have 4 computers in my home they used to all be networked with out any problem, I reformatted one to give to my little brother, when windows was finally installed I configured the computer into my work group. My main computer saw it but sharing wasn't configured for some reason, so i configured it, just after that my computer didn't see it anymore so i looked at it and it didn't even see it self in the network. so i started trying to reconfigure my work group on both comps well after doing that now my computer doesn't see anything nor itself either. but the other 2 computers saw each other when i hubed them through a 5 port hub and not my router as soon as i connected them to my router they didn't see each other so i figured it was the router, went out and bought a new one just in case, same issue, i have tried every freaken thing that i can think of, the sad thing is networks are my specialty. here are the main specs

-Computer #1 (main)--
Desktop
Windows XP Pro SP2
Win Firewall disabled
Norton Firewall enabled (have tired with it disabled)
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-Computer #2--
Desktop
Windows XP Home SP1 upgraded to SP2
Win Firewall disabled
Norton Firewall enabled (have tired with it disabled)
---------------------

-Computer #3--
Desktop
Windows XP Home SP1 upgraded to SP2
Win Firewall disabled
Norton Firewall disabled (will not enable theres an issue with it)
---------------------

-Computer #4--
Laptop
Windows XP Pro SP2
Win Firewall disabled
Norton Firewall enabled (have tired with it disabled)
Saw itself on the network but only through wireless
---------------------

-Router--
Linksys Wireless N WRT300N
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-Modem--
Linksys Cable
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Internet works through out but not file sharing
The network is setup in a Star Topology

any possible help is very much appreciated, any info you need feel free to ask, thank you