I think you have to provide a field to fill in password, something like
Code:
<tr bgcolor="{secondaltcolor}">
<td><b><normalfont>Your current password:</normalfont></b>(You have to provide your password in order to change your profile)
<normalfont><input type="password" class="bginput" name="currentpassword" value="" size="30" maxlength="30"></normalfont></td>
</tr>
before you submit the modify profile form in
modifyprofile template