why mkdir cannot work at /mnt?

[eric]

Dear gnu-linux programmers:

   After I upgrade from LM8beta1 to beta2  , I losing read, listen, or
watch iso9660 , music cd and dvd file on my cd, only think good is
cdrecord

I trace the problem is in my /mnt directory , no content at all
and I can not mkdir cdrom or floppy:

address@hidden /mnt]# mkdir  cdrom1
mkdir: cannot create directory `cdrom1': Permission denied
address@hidden /mnt]# mkdir  cdro
mkdir: cannot create directory `cdro': Permission denied

need expert's help

sincere
eric