Problem with net connection

I have HCL pc in which intel core2 Duo processor and realtek RTL8139/810X family fast ethernet adapter are there. iam using air tel LAN connection. my problem is that every time i switch on my pc for the net local area connection icon missing and not connecting to the net. on pinging showing that the host unreachable. if I instal the intel express installer drivers then the icon and the net is coming all right. this i had to repeat,each and every time i switch on PC. why it is required to instal the drivers to connect to the net every time i switch on the pc? and also suggest me a suitable solution