onboard ethernet problems

[siresword]

ive been using my ultra d for about two months, and starting last week its been strange with the internet.

 

right now i have a half working nvida nforce controller and the marvell lan also works. i can connect to my home network fine, but once connected the router does strange things with my connection. i'll be browsing the internet and then all of a sudden firefox will instantly tell me that a webpage cannot be found, and then i'll have to push retry a couple of times and things will connect. this also happens in games, like when i play 1.6. my pings are usually around 40-60 but i spike often. i think there's a problem with my wired ethernet controllers, because both have the same problem. also, my brother's wireless works fine and never gives him the errors that im getting

my windows has no firewalls enabled and i am not running any either, except for the 'firewall' that comes with my router (linksys wrt54g).

 

i tried searching the forums, but i don't think anybody has had a partially working connection

oh, and when i tell windows to 'repair' my connection , it always stops at "clearing NetBT" and never finishes the operation

 

do you know what could be causing this ?

[siresword]

does anybody know anything about this ? some kind of unstable lan from the ultra-d's ?