TP-Link WN722N usb NIC

I'm having trouble connecting to my home network using a new USB NIC I ordered from Newegg.com. I have installed the newest drivers from the manufacturer's website and tried multiple times to diagnose the problem through Windows to no avail. The closest I can come to connecting to my network is for a few seconds until it drops the connection altogether and tells me to select a network from an empty list.

I have disabled my Local Area Connection (wired) because I have read that Windows 7 (64-bit) is finicky when it comes to multiple NIC devices connected to the same network. I have also checked Device Manager to make sure that the device is functioning properly, and that it is recognized by Windows as a wireless device. I am hoping that you can give me some further insight into the problem(s) I am having.

A few errors that caught my eye:

------------------------------------------------
WLAN Extensibility Module has failed to start.

Module Path: C:\Windows\system32\athExt.dll
Error Code: 126
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Details about wireless connectivity diagnosis: 

Information for connection being diagnosed
 Interface GUID: 6614196a-1e18-4b76-afcb-b717adc7ec78
 Interface name: TP-LINK 150Mbps Wireless Lite N Adapter
 Interface type: Native WiFi

Connection incident diagnosed
 Auto Configuration ID: 2


List of visible access point(s): 0 item(s) total, 0 item(s) displayed

Connection History

 Information for Auto Configuration ID 2

  List of visible networks: 2 item(s) total, 2 item(s) displayed
  BSS Type PHY  Security    Signal(RSSI)    Compatible  SSID
  ------------------------------------------------------------------------------
  Infra  <unknown>  Yes     36  Yes     OnyxTiger
  Infra  g  Yes     32  Yes     J8IA7

  List of preferred networks: 1 item(s)
   Profile: Homesystem
    SSID: Homesystem
    SSID length: 10
    Connection mode: Infra
    Security: Yes
    Set by group policy: No
    Connect even if network is not broadcasting: No
    Connectable: No
     Reason: 0x00028002

 Information for Connection ID 2
 Connection started at: 2012-03-23 20:10:13-378
  Auto Configuration ID: 2
  Profile: Homesystem
  SSID: Homesystem
  SSID length: 10
  Connection mode: Infra
  Security: Yes
  Pre-Association and Association
   Connectivity settings provided by hardware manufacturer (IHV): No
   Security settings provided by hardware manufacturer (IHV): No
   Profile matches network requirements: Success
   Pre-association status: Success
   Association status: Fail 0x00000000
   Association reason code: 0x00000000

 Information for Auto Configuration ID 1

  List of visible networks: 5 item(s) total, 5 item(s) displayed
  BSS Type PHY  Security    Signal(RSSI)    Compatible  SSID
  ------------------------------------------------------------------------------
  Infra  <unknown>  Yes     76  Yes     Homesystem
  Infra  g  Yes     24  Yes     Merrick
  Infra  <unknown>  Yes     36  Yes     OnyxTiger
  Infra  <unknown>  No      38  Yes     OnyxTiger-guest
  Infra  g  Yes     32  Yes     J8IA7

  List of preferred networks: 1 item(s)
   Profile: Homesystem
    SSID: Homesystem
    SSID length: 10
    Connection mode: Infra
    Security: Yes
    Set by group policy: No
    Connect even if network is not broadcasting: No
    Connectable: Yes

 Information for Connection ID 1
 Connection started at: 2012-03-23 20:08:46-262
  Auto Configuration ID: 1
  Profile: Homesystem
  SSID: Homesystem
  SSID length: 10
  Connection mode: Infra
  Security: Yes
  Pre-Association and Association
   Connectivity settings provided by hardware manufacturer (IHV): No
   Security settings provided by hardware manufacturer (IHV): No
   Profile matches network requirements: Success
   Pre-association status: Success
   Association status: Success
    Last AP:  e0-91-f5-6c-67-f8
  Security and Authentication
   Configured security type: WPA2-PSK
   Configured encryption type: CCMP(AES)
   802.1X protocol: No
   Key exchange initiated: Yes
    Unicast key received: Yes
    Multicast key received: Yes
   Number of security packets received: 0
   Number of security packets sent: 0
   Security attempt status: Success
 Connectivity
   Packet statistics
    Ndis Rx: 2
    Ndis Tx: 51
    Unicast decrypt success: 94
    Multicast decrypt success: 0
    Unicast decrypt failure: 0
    Multicast decrypt failure: 0
    Rx success: 302
    Rx failure: 0
    Tx success: 395
    Tx failure: 0
    Tx retry: 0
    Tx multiple retry: 0
    Tx max lifetime exceeded: 0
    Tx ACK failure: 0
   Roaming history: 1 item(s)
     Times: 2012-03-23 20:09:48-824
    Roamed from BSSID:  e0-91-f5-6c-67-f8
     Reason: 0x00000002
 Disconnected from BSSID:  00-00-00-00-00-00   Reason: 0x00000205

I had the same problem. Tech support at TP=Link was not very helpful and they appear to be quite unfamiliar with the problem in their latest driver.

What I found was that it was a big mistake to install the TP-Link WN722N using the latest driver downloaded from the website.

I solved the problem by uninstalling the latest driver and installing the older driver (more than two years old) found on the disk that came with the product.

The product now works great on my Windows 7 64 bit home premium system. I notified TP-Link of this finding and they say they are passing the information to the right folks at TP Link. I still get the error code 126 relating to C:\Windows\system32\athExt.dll which is missing on my computer.

I'm interested in finding out why this file is missing but in my case the error is not interfering with my wireless performance. I hope this information helps.