opening "administration -> installation" once adds a cookie ZBX_CONFIG. as long as this cookie is present, opening any other page results in being redirected to the configuration wizard.

this is extremely confusing and is causing various problems every now and then.

as the cookie seems to contain some information about the current setup, just removing it might not be an option - maybe frontend can read relevant information from the existing configuration file when appropriate (thus allowing to remove the cookie), or maybe cookie could be ignored for all page except setup.php