Mr Perfect Circle:
Frankly,the problem happended at the very first begining of my mandrake linux installation,so I even can not finished my installation....,but I know the kernel must be 2.4***.
anyway,your's "check how you connected your dvd rw" really gives me a good hint!
so I am gonna go back home to see that and tomorrow I will tell you.
Thank you very much for your help.