Do you perhaps have any nfs mountpoints underneath /opt ?
Rita already pointed out your syntax error, but assuming that was just a typo you may have something else going on. NFS mounts can cause find to work *very* slowly, which may be perceived as a hang.
On the same note, find is incredibly resource intensive, especially when run from /. While the functionality of find is sometimes required, you can often use alternative, less impactive, commands to yield the same information. For simple name searches, for instance, du -a | grep works far more quickly and with less system load. When you do need to use find, try to restrict the search as much as possible either with the -xdev flag or by starting your search in as small a subdirectory as will suffice for your purpose.
