First I should mention I've set up a wifi network for my small business as over time the ethernet cords we used either got cut by accident, or damaged in one way or another. This was the main reason for just setting up a wifi network, I've got all the computers using

1. USB wireless N adapters attached to computer

2. All running windows 7

3. Wifi Router is a Wireless N

but for some reason one computer I have will not keep a connection, here is everything I've tried so far

1. I've changed 2 different d-link adapters, 1 belkin adapter, etc

2. I've let windows install the driver,

3. I've gone to d-link & belkin websites and used their drivers

4. I've manually made the adapter connect to the Router

5. I've given the adapter a manual IP address

6. I've uninstalled drivers

7. I've ping -t the router with many times request timed out, or ping times to the router of 6ms or more

8. I've even gone so far as changing wifi router encryption to a WPA even WEP and it still drops connections

9. I've pulled out the adapter then plugged it back in after a few minutes

So far the only way to keep any kind of connection is to use the ethernet cable, keep in mind I've tried all the usb adapters on other computers and they have had no problem keeping a connection. I can only assume this has to be some kind of hardware problem with the computer, but i've given all the computers the same motherboards. I've even had someone come out and try to fix it and they just gave up. Hope any of you have any ideas on this matter as I am stumped.

change the wifi channel, Fresh install on the affected machine.

Move machine location.

Is there some source of electrical interference nearby? Had a friend who's internet was slow and dropping out at night, turned out to be his bug zapper.

Are all the PC's in the office the same - swap drives with another that works well - if it is software the problem will move - if not it is ether other hardware or interference.

Add to the bug zapper, fluro lights and light dimmers.

How many computers are to be connected to a home grade wireless router at the same time? Limit is four, but can be increased by introducing access points.