All the answers I have seen so far seem to relate to HARDWARE. In a SOFTWARE context, I think it's much more common to use something like the following (this is my wording, so no official):
Warning: an irrecoverable action (formatting a disk), permanent data loss or other action that may result in an irreversible change to the system (such as deleting a user account) or damage to the hardware Caution: an action that may seriously affect system performance (memory usage), make take an extremely long time (resulting in inability to use the system), may seriously affect the system integrity (like removing password control or disabling a firewall) or loss or changes as listed for a warning that are reversible. Note: an action that may result in inconvenience or confusion or, positively, actions that may make usage easier. Regards, Simon North Technical Writer, Quintiq.