Online Insertion and Removal (OIR) of network modules is not supported on Cisco 3620 and 3640 series routers. A drop in output voltage from the power supply is reported as an OIR event. Such events on the Cisco 3620 and 3640 series typically indicate a hardware problem. Although the Cisco 3660 series does have limited support for OIR, spurious OIR events that occur without the physical insertion or removal of a network module can also indicate a problem with the hardware.
These are possible causes for a spurious OIR event on a Cisco 3600 series router: