IE5

I have a pc with win98se,in the ie5 properties the defualt home page cant modify
it was change when computer was on internet
even i change it it back after restart.
I delet the defualt home page from regedit but it back when restarting.
one filein cookies cant be delet ecxept from dos
called index.dat and it back after restart.
I scaned the drive no virus found.
the defult site is(lolitafucker.com)
pls help me