It is observed that the device can crash when you use the Remote Network Monitoring (RMON) to copy a configuration to the running configuration. In some scenarios, it is seen that if the power-off-switch comes back with power-on, the whole stack crashs and reloads.
This symptom is observed on a Cisco routers that runs a Cisco IOS software image that integrates the fix for Cisco bug ID CSCeg74543, which says Cisco IOS images after Cisco IOS Software Release 12.2(25)S can see configuration sessions become unresponsive.
This problem is documented in Cisco bug ID CSCsd37284.
In order to resolve this problem, you can upgrade to Cisco IOS Software Release 12.2(35)SE1, which can be downloaded from Cisco Downloads.
If an upgrade is not immediately possible, then the only workaround is to disable RMON. Refer to the Configuring RMON for more information.