internet explorer problem

First we thanking all of you to have joing best forum in world.

I have desktop E520 with window vista home premium my problem is i have spectranet brodband connection when we go to connect internet my system is not fully log in when other computer at same network  first log in and enter username & password after my system can access web page otherwise just stop before login came. i restore system two and thrice that problem is solved but when compure re-log  next time problem as it is as before. please advise any solution for above matter.

thanks