Update - may be an IE9 compatibility issue. Student pc is on IE9 and tutor reporting issue believes her machine has just been upgraded to that browser. My own pc is on IE8 which may be why I couldn't recreate the problem. Bug filed by someone else yesterday https://bugs.launchpad.net/mahara/+bug/861891 describes a similar issue with IE.
Update - may be an IE9 compatibility issue. Student pc is on IE9 and tutor reporting issue believes her machine has just been upgraded to that browser. My own pc is on IE8 which may be why I couldn't recreate the problem. Bug filed by someone else yesterday https:/ /bugs.launchpad .net/mahara/ +bug/861891 describes a similar issue with IE.