VFAT read-only???

Hi,

I get something strange with a vfat partition:
Window$98 is installed on /dev/hda1

I save/restore this partition from /dev/hda3 using tar.

Today I delete nearly everything in /dev/hda1 (/mnt/win).
Nearly because, I can't delete windows directory.

It tells me:
rm: unable to remove '/mnt/win/windows/Setup533/Ca533av.sys': Read-only file 
system
...

I try:
# echo "coucou" > /mnt/win/test.txt
cannot create /mnt/win/test.txt Read-only file system

But:
# mount
/dev/ram0 on / type minix (rw)
none on /proc type proc (rw)
/dev/ram3 on /tmp type minix (rw)
/dev/hda1 on /mnt/win type vfat (rw)

Why does it happen?

Should I format /dev/hda1?
I'll do it because of lack of time, but is there another solution?

Thank you very much.
-- 
Stephane Boireau
Personne ressource TICE du collège Le Hameau à Bernay (27)