There are any number of other possible or potential problems
One may be the encryption you are using on your WiFi, try experimenting.
First by temporarily running it "Open" without any encryption, and then progressing up through WEP to WPA, WPA2 and then try experimenting between AES and TKIP on your router.
Second, some have reported problems with Dell wireless radios because of the mode settings.
Go back into device manager
expand network adapters
select then right click the problem wireless adapter and choose properties
select the "Advanced" tab at the top
In the left column titled "Property:" see if you have a BSS Mode (or anything related to something called "MODE") listed. If so select it and in the right column titled "Value:" use the drop down arrow to change from 802.11n to 802.11g (or basically, from whatever it is to another option) it might be set to b,g,n or n only, the idea is to try sampling different modes.
OK your way back out of there and reboot and see if that helps.