Steps of replication:

1. Create a group called "Sample"
2. Go to Project Role Browser
3. Click on the Manage Default Members link
4. Select Default Groups
5. Add "Sample" group to the project role
6. Remove the "Sample" group from the project role

Here is the page source:

<td valign="top">
       <a id="group_link_"Sample"" href="/secure/admin/user/ViewGroup.jspa?name="Sample"">"Sample"</a>
        </td>
        <td align="absmiddle" width="1%" nowrap>
             <input type="checkbox" name="removegroups_"Sample"" value=".">
         </td>
</tr>

It seems like the double quote breaks in the middle of the link.