这是怎么回事啊？怎么解决呢？

这是因为你的安装目录里少了一个文件。这个文件是AI所必须的。所以才有这种情况
解决方法参照：

[url]http://kb.adobe.com/selfservice/[/url] ... 31889&sliceId=1

其中的一种方法，你要先把系统的隐藏文件夹和文件属性去掉，然后查找到：

1、如是 Windows Vista 把如下的路径的 AIPrefs 文件更名为 AIPrefs_old ：

C:\Documents and Settings\用户名\AppData\RoamingAdobe\Adobe Illustrator (版本号) Settings

如是 Windows XP 路径为：

C:\Documents and Settings\用户名\Application Data\Adobe\Adobe Illustrator (版本号) Settings

2、启动 AI 即可。

如果还不行，请删掉整个预置文件夹的东西(之前请备份)，再试试。

原文：

引言回覆:
Solution 1: Re-create the Illustrator preferences file.

Re-create the Illustrator preferences file to eliminate problems that a damaged preferences file might cause.

Note: When you re-create the preferences file, unsaved actions are lost. To save actions that you created, choose Save Actions from the Actions palette menu.

To re-create the Illustrator preferences file:

     1. Quit Illustrator.
     2. Rename the preferences file or folder:
                 * In Windows Vista, rename the AIPrefs file in the Users/(user)/AppData/Roaming/Adobe/Adobe Illustrator [version] Settings folder to AIPrefs_old .
                 * In Windows XP, rename the AIPrefs file in the Documents and Settings/[user profile]/Application Data/Adobe/Adobe Illustrator [version] Settings folder to AIPrefs_old .
                 * In Mac OS, rename the Adobe Illustrator [version] Settings folder in the Users/[User]/Library/Preferences folder to Adobe Illustrator [version] Settings_old .
     3. Start Illustrator. Illustrator creates a new preferences file.

Note: If re-creating the preferences files does not resolve the issue, then delete the old preference files or, if you have customized preference settings, then delete the new preference files and remove the _old from the original preference file name.

Solution 2: Delete the com.adobe.illustrator.plist file (Mac OS only).

Delete the com.adobe.illustrator.plist file(s) located in the [User] /Library/Preferences folder.

Solution 3: Install and run Illustrator in a new user account.

Create a new user account with the same permissions as the account experiencing the error, and then install and run Illustrator under that account.

For instructions on creating a new user account, see "To add a new user to the computer" in Windows Help, see "Adding a new user account to your computer" in Mac OS Help, or contact your system administrator.


汗，那里也都有列有参考了(我偷懒少翻译一下也不行  )：

Mac OS 下：

方法 1、重新命名在Users/[User]/Library/Preferences 文件夹下的 Adobe Illustrator (版本号) Settings 文件夹为 folder to Adobe Illustrator(版本号)Settings_old .(你的是 AI CS3 版本号就是 CS3)

方法 2、删除位于 [User] /Library/Preferences com.adobe.illustrator.plist 文件

方法 3、创建新的用户安装运行 Illustrator ，要注意赋予该用户与你运行出现错误的用户一样的的权限。

楼上的有经验哦