when an error occurs it checks the code version vs the version of mojoportal-core in the mp_SchemaVersion table. If it can't access that table or if the version is lower than the code version it will redirect to setup because it wants to run the database upgrade scripts to bring the 2 versions in sync.
Looks to me like you are running a very very old of mojoPortal possibly a version where the code has been modified.
The Search button definitely is some custom feature, not something that is part of mojoPortal.