我也遇到这个问题，开始想写句VBScript放在启动里，每次开机的时候跑一下。无奈水平太菜，写不出来。
找了很久，终于找到了真正的元凶----快速启动栏。只要把它隐藏起来（任务栏空白处按右键-->工具栏-->快速启动），重启开机后，任务栏的宽度就不会变化。
但没有了快捷启动栏不方便，怎么办了。下载一个Free Launch Bar代替。问题完美解决。
A trick that usually works to fix the problem you're having is to disable the Quick Launch toolbar. The Taskbar should then resize itself back to normal and then you can re-enable the Quick Launch bar (right click on and empty space on the Taskbar, point at Toolbars, click on Quick Launch to remove the check to disable, do it again to replace the check to re-enable).
ref: http://www.softwaretipsandtricks.com/forum/windows-95-98-me/20673-1-1-2-taskbar-height.html
