故障现象：

所有未知格式文件打开的时候，则跳出该文件拒绝访问当点鼠标右键直接选打开方式的时候也会弹出该文件拒绝访问警告窗口;如果右方已经有部分程序列表，则在点右侧次级菜单中的选择程序时跳出该文件拒绝访问的警告.

故障诊断：

未知格式文件打开方式关联被恶意修改.

解决方法：

把下面的代码放到记事本中去，改名为*.reg 文件，双击它就会把信息写进注册表，之后就解决问题了!

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOTUnknown]

AlwaysShowExt=

QueryClassStore=

[HKEY_CLASSES_ROOTUnknownshell]

@=openas

[HKEY_CLASSES_ROOTUnknownshellopenas]

[HKEY_CLASSES_ROOTUnknownshellopenascommand]

@=hex(2):25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,00,25,

00,5c,00,73,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,72,00,75,00,

6e,00,64,00,6c,00,6c,00,33,00,32,00,2e,00,65,00,78,00,65,00,20,00,25,00,53,

00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,00,25,00,5c,00,73,00,

79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,73,00,68,00,65,00,6c,00,6c,

00,33,00,32,00,2e,00,64,00,6c,00,6c,00,2c,00,4f,00,70,00,65,00,6e,00,41,00,

73,00,5f,00,52,00,75,00,6e,00,44,00,4c,00,4c,00,20,00,25,00,31,00,00,00

*号要用字母代替复制红色区域的内容后，粘贴到记事本中，另存为如 1.Reg然后双击导入注册表即可