I have solved the problem with mounting files under RH7.2 It was nothing to do with my kernel compiling escapades. I started linux at run level 3 and tried mount/umount and lo and behold they both worked on CD and floppy. Issued a startx andwow they still work in X. So its not a mount problem per se and its not an X problem either. Must be rcd differences between level 3 and 5. Check these out and find I have turned of apm daemon in level5 (amongst other changes). Turn this back on, reboot and all is well again. Now this is not a laptop PC although it is basically a laptop with a built in PSU. SO I thought I have no need of battery management as I have no battery but apm obviously has wider power management abilities than I had imagined.
Ian