Are you using any 3rd party utility manager to wireless connect? If you do, you have to disable the Wireless Zero Configuration (WZC) for XP and WLAN Auto Config
for Vista/7 from Control Panel's Services. If not, the WZC needs to be Started.
Control Panel\System and Security\Administrative Tools, locate WZC or WLAN Auto Config and Disable.
Download the most recent driver for your Wi-Fi Adapter, it might help. You may obtain the latest driver from the Manufacturer's site.
Disable the problematic Wireless Network Adapter's power saving mode from Device Manager, locate the Network Adapter=> Properties=> Power Management Tab, in here you may disable any Power Save mode options by unchecking them off.
If above recommendation didn't help at all please provide an ipconfig/all:
Click on Start => in run or search box type cmd press enter choose Run as Admin. Open up a command prompt then Copy and Paste these ipconfig /all >c:\ipconfig.txt . Please attach the .txt file to be found in your Local Disk 'C' on your next post.
Also, Device Manager you may disable any Power Mode options of your Wi-Fi Adapter.
Also, from your wireless computer pls. install and run Xirrus Wi-Fi Inspector
Click on the 'Show Networks' to display all wireless networks on the xirrus icon on your desktop of if you have one running in a corner. Tap the Printscreen key on your keyboard, open up Paint then choose Edit from the Menu and select Paste, then SAVE it. Upload and attached it here, click on Go Advanced and locate Manage Attachments Tab and attached the file.