win7下安装matlab R2011b(或R2012b)都遇到同一个问题，就是添加下载的工具箱修改 set path 保存时，会弹出
matlab cannot save changes to the path
  the path file,pathdef.m might be read-only or might be in a folder for which you do not have write access···do you want to save pathdef.m to another location.
根本无法保存，添加。所以请问大家有遇到这个问题是怎么解决的呢？
我参照网上说的以管理员的权限打开matlab，再添加路径，一样不能保存？可以通过什么途径来修改pathdef.m的权限么？