My computer is getting stuck when i login for the internet bt it works fine in safe mode or if i dont login

I hav xp sp2... intel desktop board D945GCNL....built in real tek lan ....i m using this computer 4m past 1 year bt i had no such problem...its 4m last 15 days..i formated twice still...sum1 plz find me out a solution 2 my problem....i m usin internet in safe mode...da moment i use internet in normal mode my pc gts stuck n i hav 2 restart.if i dnt use internet in normal mode it works just fine.. ....