Windows was unable to find certificate to log on to the network

This type of error message appear when we are trying to connect to the wireless network.
For Windows(xp) perform the following steps:-
a)click on start menu and then go to control panel and then open network connections from there.
b)Under network connections an option for wireless connection exist , right click on that option and then click on properties.
c)Under wireless network connection properties there are three tabs general , wireless network and advanced.
d)Left click on wireless network tab and check the box which says use windows to configure my wireless setting's and click OK at the bottom.
e)Then , Right click again on wireless network connection and click properties and then again click on wireless network tab.
f)At the bottom of the wireless network tab you will have preferred networks and in that small box yo will have list of networks and therefore delete all of them from there including the one you are trying to connect to.
g)On the right hand side of preferred networks you will have ADD click on that option and enter the details of your network manually.
SSID(name of the network)
Network Authentication:-Open if the security is WEP else WPA-Personal.
Encryption:-WEP for wep security TKIP/AES for WPA-PSK.
Network key/Confirm network key:-is the wep key or wpa-psk password.
Untick the box at the bottom that says the key is provided to me automatically.
Click OK at the bottom and close the properties window.
h)Then , Right click again on wireless network connection and then left click on view available wireless network.
i)List of available networks will be there , select the network you use and try connecting to it , it will get connected automatically.

I have a laptop that connects to wirless router like normal.The router is belkin g wirless.But i want to RE connect my dads computer to it.I say RE connect because up until last week in was connected to it and working.But then a box came up saying windows cannout connect to log certificate authencity,or something like that.Now my dads computer isn even picking up the wirless network.It doesn show up when you search for it.I followed the steps on your site but still had no luck.