hmm, try this on the terminal;
this should make a directory in the current home called ntfs and try to mount it read-only, and show you any errors in the process. If it can't find 3g try just "-t ntfs" or don't give it a -t and it'll try to auto detect
Code:
mkdir ~/ntfs
mount -t ntfs-3g -o ro /dev/sdb1 ~/ntfs