Iridni put on the ring "Keepers Guide" (think that's what it's called) to supplement her Search skill. She had Detect Mode activated when she put on the ring, which was slowing her movement. When she tried to deactivate Detect Mode, she received the message "You may not disable this mode. Characters with Keen Senses always receive the benefits of active search mode." So the ring, which should have been allowing passive Detect, locked her into slow-movement Detect.
Fixing it required removing the ring, deactivating Detect Mode, and then equipping the ring. Not a big deal, but it kept her locked in slow movement, which can be deadly when suddenly needing to flee.