I have a (deeply nested) directory on an SDHC card that is maintained via subversion. I encountered problems with some files (my own screw-ups with svn consistency), so built a new version of the directory from the repository. Now I just want to delete the old version, but don't seem to be able to. 'rm -f -r *' while root got rid of most, but two quite large nested directories remain. The files that can't be removed have ownership user:root and permissions 644. When I try to remove them, each file gives the message
rm: cannot remove <filename>: Read-only file system
yet the problem is clearly not an RO FS, because other files in the file system were removed with no problems.
Does anyone have any clues:
.what is actually happening?
.what can be done about it?
TIA for any help.

In case it's relevant:
N800
OS2008
8GB SDHC card, default formatted (I think that's FAT16, right?)