This guide already well known to the world, but still worth to be shared. :) Let me describe about the issue on the title of this post. "Red X mark on the wireless signal bar on taskbar".
The issue :
>>>> Occur in windows 7 <<<<
1) When you click on the signal bar, you can see available wireless connection.
2) You can connect to the network you see.(provided that the wireless network not password protected and
Now you see the issue. Your computer giving you a false icon / falsenotification. It should be a wireless signal with orange X symbol.(If you're not currently connected to any network).
What cause the wrong icon???
1) Some suggested that the icon doesn't belong to the wireless adapter but it belongs to your LAN adapter.
1.1) Delete other Adapter present in the Change Adapter Setting except LAN adapter and Wireless
adapter. Click on the Wireless Signal Bar on your taskbar > Open Network and Sharing Centre > On the left tab, click Change Adapter Setting > Right click on the LAN adapter >
1.2) You need to disable and then enable your LAN adapter.
Click on the Wireless Signal Bar on your taskbar > Open Network and Sharing Centre >
On the left tab, click Change Adapter Setting > Right click on the LAN adapter > Disable
If you lucky, step 1 should solve the problem. But if step 1 didn't solve the problem,
2) Go to Device Manager and uninstall your wireless driver but don't delete(don't tick the remove driver
box) the driver. After uninstall, restart your laptop.