Due to the changes in a robot name or IP (or other changes that alter the robot binary code), the robot's probes' magic keys are invalidated. The magic_key is essentially a checksum that is based on a hash of the robot name, ip, and a checksum of the binary for the probe. If any one of those things changes, the checksum calculated will no longer match the recorded magic_key. In IM, choosing rt-click-> Security-> Validate->Yes to All forces a re-write of the magic key to the new checksum. It's a security check. Otherwise, someone could replace a probe executable with something they had written and it would then be run with the security level of the monitoring software rather than the user.
Component : UIM - ROBOT
Unified Infrastructure Management (UIM), any version