[Users] "detached" timer

Does anyone know what causes this? */set_timer for 1 list called on a "detached" timer -- ignoring /* I also see */set_timer for 3 list called on a "detached" timer -- ignoring /* When this happens Openser seems to lock up for 10 seconds or so. From searching it appears this is caused by a race but I am not sure what the race is or why this results in an unresponsive openser instance for multiple seconds. Transaction expiration racing reply? Desperately need to understand how this could be triggered so I can get customer to adjust system. Any way to adjust? tried tweaking fr_inv_timer but no joy. TR