My adapter only works randomly with my network. No problems with my MAC which has a strong and consistent connection. Do I need an update?

I had the same problem I have a ZTE USB modem & when I connect it with mac it never show up...so I googled ZTE for Mac & I found a driver update & update for connection manager . After installing them the modem work as charm

Your problem it seems to be a router problem. If on router side, you have enabled the access protection based on devices MAC addresses, then you must add the new adapter's MAC address into the router's MAC list with allowed devices that are able to reach the internet. For this, you must enter into your router admin settings via http and go to the security section and update the MAC list with allowed devices by adding your new adapter's MAC address. On my router, if I must permit to a new device to go to internet, I have two sections to update: "Wireless->MAC Filtering->Update allowed devices" and the second one is: " Security->MAC Filtering->Update allowed devices "
Good luck!

You mentioned that you have Windows XP SP1... You need to install at least SP2 or even SP3 for this adapter to work. If this computer doesn't have internet access at all, then you can usually get SP2 or SP3 on a disc for free from Microsoft.

At times, a netbook or notebook can create multiple duplicate links to the same network. Each one will diminish the strength of the connection by a little bit and you should clean them out so that there is only one.

Also, it makes sense to use the MAC address on the server side, such that only a netbook with your unique MAC address can connect to the wireless connection. It saves energy/strength if that is your only real security stopper, since like fingerprints, there are no such things as duplicate MAC addresses.

Try making those changes you might just find a cleaner, stronger connection to your WiFi at home.

Good Luck,
-a.

Check that the wireless adapter is correctly installed -- correct device-drivers loaded.

Check that the wireless adapter is not "disabled" (a slider switch?)

Try the wireless capabilities of the Mac at a "hot-spot" (Starbucks? Public Library?) to see if it can connect to *ANY* wireless network.

Run the Apple Software Updater, to ensure that OS X is properly updated.

Check that the Mac is connecting to the correct SSID, with the correct password/passphrase.

This means, that either the password is incorrect after all, or the router/access point to which you are trying to connect has some filtering enabled for security reasons - usually it's MAC address filtering, to allow only specified network adapters (hence - computers) to connect.
You have to contact the person that set up the router/access point.

At last, I have finally resolved the issue, sometimes the solution is so somple that you totally miss the solution. It was as simple as the Windows Firewall ( switch it on ), I have a Mcafee security center protecting my network and it wouldn't let me connect with additional protection. Also, I entered the wrong mac address on the routers (access control) settings. I'm now on the internet. Obviously I have to big up Mcafee for excellent security controls. So if anybody else ever has the same problem follow these simple steps.

1. Check all of the settings that I described in the original question
2. Make sure Firwall settings are correct (& active).
3. Check your routers homepage ( access control truly works).
4. Make sure you you enter the correct MAC address (use the MAC address of the wireless network adapter, that's what connect you to a network) i.e. 00-01-a2-11-22

check for firmware update for your adapter...since it usb..u need to put it in open..i believed the USB extension is included when u purchased that.

do not connect the USB adapter to a USB hub unless the HUB is powered so that it can performed better. Connect it directly to your PC slot

Might be several things, but perhaps start with checking for any driver updates that might be available.

There is no way to change the MAC address, but you can make Windows tell the system it has a different address that might fool your other program. Follow the instructions below.
Change the MAC address in Windows

1. Go to Start -> Control Panel. Double click on Network Connections (inside Network and Internet Connections category in Windows XP). The, right click on the active network connection with network adapter that you want to change the MAC address (normally Local Area Network or Wireless Network Connection) and click on Properties. Above steps work in Windows XP, Windows 2000 and Windows Server 2003 . For Windows Vista, access to NIC’s properties is from Control Panel -> Network and Internet -> Network and Sharing Center -> Manage Network Connections.
   Alternatively, if you already know which network adapter that’s responsible for your network or Internet connection, go to Device Manager and open the properties dialog by double click on the NIC itself.
   
2. In the General tab, click on the Configure button.
3. Click on Advanced tab.
4. In the Property section, select and highlight Network Address or Locally Administered Address.
5. To the right, “Not Present” radio button is by default selected as value. Change the value by clicking on radio button for Value:, and then type in a new MAC address to assign to the NIC. The MAC address consists of 6 pairs of numbers (0 - 9) and characters (A - F) combination. For example, 88-17-E8-90-E2-0A. When entering the new MAC value, omit the dash (-), for example 8817E890E20A.
   
6. Click OK when done.
7. To verify the change of MAC address, go to command prompt, then type in one of the following commands: ipconfig /all
   net config rdr
   
8. Reboot the computer if successful to make the change effective.