Coding Horror notes that most users simply ignore dialog boxes and simply dismiss them without actually reading them or understanding what they mean.
This is a result of the overuse of dialog boxes. According to the original Macintosh Human Interface Guidelines, a dialog box should only be used for an exceptional condition that requires immediate user action. Over time this rule was ignored and most software now puts up a dialog box for every little thing and in most cases it’s inappropriate.
Users become desensitized to dialog boxes since they appear so often and simply dismiss them immediately. Windows Vista has made the situation worse with the frequent security confirmation boxes. After a short time, users simply keep pressing ‘accept’ without understanding the situation.
Sheets in Mac OS X are a step in the right direction, since they appear in the window they apply to and are related to the user’s current activity, such as printing or saving the document.
As the article points out, software updates are a prime area where alerts can be eliminated. The user shouldn’t be prompted for important security upgrades; they should simply be downloaded in the background. If a reboot is necessary, they should simply display an icon in the menu bar to notify the user. Most operating systems have such an option. It should be made the default, since that’s the best option for unsophisticated users. More advanced users can change it.