I have an error when trying to view my HD
 

I have an error when trying to view my HD. it says Nautilus has no viewer capable of displaying /dev/hda i have redhat9

Well most likely you can't just view /dev/hda.. Its most likely going to be split into partitions which are mounted, like /dev/hda1 would or can be /boot and /dev/hda2 could be your / directory with all the other directories within it. What exactly are you trying to view, files, etc? Use the ls command and cd command to navigate thru your filesystem. But you can't just view raw devices in /dev if that is what your tying to accomplish.

I want to view files

all fixed