Loss of wireless connection

I am currently running Windows 7 on a Acer Aspire. I have a Belkin Basic N150 Router and Belkin Basic N150 Usb Adapter. I am running on Qwest VDSL 12M Up/1.5M Down on a Qwest ZyXEL Q100 modem. The router and modem are wired to my Windows XP system in a room that is only 22 feet away seperated by a wood door/normal house walls. The wireless usb adapter is plugged in to my Windows 7 pc which like I said is only 22 feet away and is up high off the ground with perfect line of site other than the door. I have no wireless devices in the house other than the computer attached to it and my cellphone. Both the router and the adapter are less than a month old and have been firmware updated to the latest as of 2 days ago. I have all the Windows updates installed on both computers and the modem was firmware updated by Qwest 1 week ago. Router is set to WEP security on channel 11 with 802.11e/WMM QoS enabled and the SSID is been changed. Firewall has been disabled and DMZ has been enabled.

With all that said here is the problem I am having while I am surfing the internet for extended periods or watching a movie streaming or downloading something or in some cases I go to work and come home hours later, I find that my wireless computer is no longer finding the network. If I open the wireless connections search box it does not even show the wireless on the list.

When this happened the first few times I tried rebooting the system with no avail still no connection. I even tried turning WiFi mode on on my Nexus One cellphone and do a search for WiFi and I dont see it. The only thing that seems to work is going in to the room unplugging my router waiting a few seconds then plugging it back in waiting for the light to turn green then go and find the network on the wireless computer and *poof* there it is. By the way I tried plugging a direct ethernet from the router to my Blu-Ray device when this happened and the internet still worked was able to load Netflix just fine. Also the computer wired to the router worked just fine. Only the wireless goes down.

Any suggestions as to what could be wrong and what I could do would be greatly appreciated. Just to let you know options like "Well buy a new router" or "Buy a new computer" wont work I don't have the money for anything new right now this is what I have to live with. If you need any other specs of my stuff or settings I currently have on my computer let me know I will post. Thank you for your time and expertise.

Addendum:

The speed at which the internet runs on this computer seems to me very slow. Even though the speedtests on various sites registers it at 12mb/up roughly. Downloads and torrents seem to go at about 100kb/s - 450kb/s I have never had it go above 1mb/s on any download. Webpages load almost like they did on my ISDN way back in the day.

It happened again this morning. Please Help.

What is your reason for enablig DMZ on the router, disable it and check things again to see if it will reoccur

I tried both ways. I enabled it though cause I was told to do that since I was having a hard time with downloading torrents. But I have tried both ways with it off it still does the same thing.