Can't seem to run df -h /
 

I'm trying to run df -h in terminal to see what's clogging up roottf.
It says "Mounted on /etc/mtab: No such file or directory". Then I try df -h / and it says "can't find mount point"

Does anyone know what the problem for this is?

Looked in conky and it says i have about 200mb(approx) free, but when I try to install Faster App Manager it says I have no free space. I also tried to uninstall apps, but it gives me an "internal error, app manager closed"