飞机对化妆品的要求:c://WINNT/system32/drivers/etc/hosts是什么

电脑经常弹出广告，查用了雅虎助手查出c://WINNT/system32/drivers/etc/hosts文件被改了，正常的：
# Copyright (c) 1993-1999 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
# 102.54.94.97 rhino.acme.com # source server
# 38.25.63.10 x.acme.com # x client host
127.0.0.1 localhost

我的：
127.0.0.1 sds-qckads.com
127.0.0.1 status.qckads.com
127.0.0.1 www.qoolaid.com
127.0.0.1 www.qoologic.com
127.0.0.1 www.CLKPrecision.com
127.0.0.1 www.urllogic.com
127.0.0.1 www.clkoptimizer.com
127.0.0.1 www.isearch.com
127.0.0.1 isearch.com
127.0.0.1 www.idownload.com
127.0.0.1 idownload.com
127.0.0.1 www.mytotalsearch.com
127.0.0.1 mytotalsearch.com
127.0.0.1 www.lop.com
127.0.0.1 lop.com
127.0.0.1 www.websearch.com
127.0.0.1 websearch.com
127.0.0.1 www.page-not-found.net
127.0.0.1 page-not-found.net
127.0.0.1 www.isearchhere.com
127.0.0.1 isearchhere.com
127.0.0.1 as.adwave.com
127.0.0.1 sr.adwave.com
127.0.0.1 www.adwave.com
127.0.0.1 adwave.com EVENT:HOST:127.0.0.1
127.0.0.1 www.pacimedia.com
127.0.0.1 www.exactsearch.net
127.0.0.1 www.contextplus.net

我改了保存，在打开后还是老样子，请教如何解决！