解决打开CHM文件，出现"取消操作“的怪现象

Having trouble viewing the files? A recent security update (Security Update for Windows XP - KB896358) has modified the behavior of files you download from the Internet. After saving the file locally (for example, to your Desktop), try to open the file. You'll see a message that looks like this:   To view the content in this file, click to clear the Always ask before opening this file check box, and then click Open. Or, right-click the file, click Properties, and then on the General tab click U