microsoft management console 求救

Adiministrative tools下的所有MMC文件都不能正常使用，如Defragment. 錯誤信息如下：
This may be because the file does not exist, is not a MMC console, or created by a later version of MMC.　This also may be becaue you do not have sufficient access rights to the file.

我以管理員身份登錄，而且下載按裝了MMC3.0, 還是不行。
請各位不吝賜教。謝謝！