I have just the same problem. I can't even make any directories. I always get that read-only file system - error.
This problem appeared when i configured samba to network my windows and linux computers. Might that be some sort of reason why i get error like that?
I have also thought if i my hard disk is broken. I had some sort of problems with one part of my hard disk when i had XP, but now i havent got any problems before this appeared.
Thanx for help, i really need it