To be able to display headers information in the PageInfo tab of Mozilla/Firebird, the nsHeaderInfo component must be registered. This component is found in the file Mozilla/Components/nsHeaderInfo.js.

Normaly, this is done automatically by the LiveHTTPHeaders installation. However, this doesn't work sometimes. So you need to follow the steps bellow to force Mozilla/Firebird to found and register it.

This two files should be recreated automatically by Mozilla/Firebird at the next start.