This Knowledgebase article provides information about how changing network configurations during the registry-checking phase can cause Neverfail Heartbeat to fail to synchronize the registry.
Due to the way Windows stores configuration changes in the registry under different control sets, if the user changes a network configuration while the registry is being synchronized, then the old configuration information will be propagated to one of the other currentControlSets. Should these changes result in different permissions being set on the key, then the registry checker may be unable to access the newly created keys.
This is purely dependent upon the progress the checker has made through the registry and whether it is processing the keys at the time of the configuration changes. The registry does not take long to synchronize, so for this reason, the network configuration should not be changed during this period. Once the registry status has been set to insync then it is safe to make any changes.