我的计算机装的系统是WIN98,正中启动中或启动完毕后不到一分钟就会死机,但是将它启动到DOS不管用多长时间都没事,当我把模式改为安全模式启动时出现以下提示,HIMEM.SYS has detected unreliable XMS memory at address 00AB15E XMS driver not installed.当我打回车的时候就会出现以后内容:HIMEM.sys is missing .Make sure that the file is in your windows directory.这两句英文的大概意思是什么我如何才能把它弄好呢?