求救！XP SP2下 开机 NSIS ERROR

小弟最近装了XP SP2，不过每次开机都会报错，但是系统无异样；
运行很多已安装或未安装的.EXE文件时也出现这个错误；
瑞星升级，金山升级，网络游戏，网页，都打不开
报错如下：
The installer you are trying to use is corrupted or incomplete.
This could be the result of a damage disk,a failed download or a virus.
You may want to contact the author of this installer to obtain anew copy.
It may be to possible to skip this check using the /NCRC command line switch(NOT RECOMMENDED).

请各位大大帮帮忙解决，究竟是出了什么问题!!!