A Network Issue

First of all, I was unsure as to if this fell under Microsoft Windows or the Hardware sections because I am not sure what is causing it, so here it goes anyway.

PROBLEM:

I have a network of about 5 computers in my apartment (1 latpop, linux box, 3 winXP machines). The problem that is occuring is that when I communicate between 2 computers the connection is EXTREMELY SLOW.

Note: It's only slow between these two computers (both running windows xp)

The network is a wireless network with 3 computers connected via wireless and 2 computers connected via cat5. The two computers that are experiencing slow connection are in different workgroups, but I have tried putting them in the same to see if that makes a difference at all, and it doesn't. The problem only started occurring about 4-5 days ago, before that everything was fine. I can't remember what has changed since then either. I have run virus scans on all of my computers and come up clean on all of them. My router is a DI-624 router using WEP encryption and MAC address filters to allow only computers listed access.

I really have no idea what is causing the slow connection between computers, but if anyone has any suggestions at all, it would be much appreciated. Thank you.

Those two computers are connected with cat5 or wireless?

I have actually tried both. Currently one computer is connected via wireless, and the other is connected via Cat5.

I did try both connected via Cat5 and saw no difference

I can think of two or three things here. I had this problem before and it turns out to be a faulty NIC on one computer, but you can try to change the cat5 cable first or shutdown your antivirus to narrow the problem.

Turned off antivirus and it still is super slow.

=(

what about turning off firewalls? and did you try switching out the nics?
also, are they running different versions of service packs? how updated are they? did you try reinstalling the drivers for the nics? have you tried them both wireless? have you tried different cat5?

They both have winXP SP2, fully updated. I haven't switched out the NICS yet or reinstalled drivers. I'm going to try that tomorrow when I have time, and let you know then. Thanks!

you're sure the cables are in good condition? also, have you tried different ports on your router/switch/hub.?

well the thing is I haven't tried multiple cables or ports, but why would the same problem persist with either the wireless connection or the wired connection (using the onboard NIC) because they're two different NICS. I'd find it hard to believe if both NICs had the same issue.

It's not necessarily both NIC's, it could be only one.