Make sure you are up to date with the latest version of the Fritz!Box Standard Firmware.

The current version at 18th March 2012 is 84.05.06

The latest version can be obtained, as a File, by downloading the latest copy of the BETA Firmware.
This BETA Firmware Package contains a copy of the latest Standard Firmware.

If you follow the AVM Links you find that the Standard Firmware is offered only as and Online UpDate.
Of course you cannot UpDate from BETA Firmware to Standard Firmware.
If you are running the BETA Firmware and need to revert to the Standard Firmware obviously you will need to install, the latter, from a File and then update the Firmware Settings afterwards.

You may have a suitable copy of the Standard Firmware residing on your HDD, look inside the Package from which you installed your BETA Firmware.

Probably the most important next move is to BackUp or Save a copy of your Fritz!Box Standard Firmware complete with any Settings that you have made. This can be achieved by following the directions, which although written for the Beta Version can be used as a guide, at:

Fritz!Box BETA [or Lab] Firmware BackUp

The following Topics aim to inform and help Users of Fritz!Box Standard Firmware.
If you notice that there are UpDates, which make existing content irrelevant and that escape our notice for more than a couple of days, please give us a ‘nudge’ by sending a Private Message [PM].

This Post will be updated with additional content so revisit occasionally. Last UpDate 18th March 2012