HELP! My MacBook Pro gets kicked off my network when a PC is connected

I have a secured wireless network using an AirPort Extreme Basestation which is a little over a year old (my internet provider is AT&T DSL). When I am the only one on my network I have no problems, however, when my husband (or someone else) connects to my network on a PC I have all sorts of problems. I am often kicked off my network and my wireless printer will not print properly as well. I am using an N network and I have even had my airport card and some sort of antenna replaced by Apple in the last 3 months to try and correct the problem.

Do anyone have any suggestions on an easy fix for the problem? I am a full time pharmacy student and need to be able to complete research assignments as well as online (timed) assignments without being afraid that my answers will be lost. Would adding an AirPort Express help? PLEASE HELP!!!

Sounds like an IP address conflict. Is the Airport set up to distribute a range of IP addresses using DHCP? Are all your computers also set to use DHCP?

I'm not sure about the DHCP? How to I check that?

have the exact same problem. strangely enough it is wore during the daytime but in the evening it gets better. have you managed to solve it?