Some time ago I wrote about bad UX at Albert Heijn (jul 2010). In short my complaint was that the check out system - on approach - very much emphasized the second step of the check out process. The first and mandatory step in the process is presented very inconspicuously.
Apparently designers at Albert Heijn are aware of this issue but unfortunately they solved it by showing a big red error message if the user accidentally scans his/her bonuskaart before putting the scanner back.
IMO this is the wrong solution for the design problem (being the user has to execute two actions in a specific order). It would be better to change the visual hierarchy of the 'welcome screen' to help users execute the actions in the right order.
Or even better, make it 2 screens; the first saying 'put your scanner back', the second 'scan your card'. I think this would very much reduce confusion and nearly eliminate the need for the big red error meesage.
But the best solution would be to design the system in such a way that the 2 actions don't have to be executed in a specific order. From a user-perspective there is no logical reason why he/she has to put the scanner back before scanning their bonuskaart!