thank you for your help, Nyll...
I have done as same as the post, but still not solved....
I uninstall Sl & delete all files about SL
then restart PC, install SL again,but not fixed...(
i have to fill name and password every time when I log in... erro message is "We can't fill in your user name asnd password. This may happen when you change net work setup" but I neve rchange sothimg someone help me..