PROBLEMAS para el euro:

Ordinary Germans have begun to reject euro bank notes with serial numbers from Italy, Spain, Greece and Portugal, raising concerns that public support for monetary union may be waning in the eurozone's anchor country.

[...] People clearly suspect that southern notes may lose value in a crisis, or if the eurozone breaks apart. This is what happened in the US in the Jackson era of the 1840s when dollar notes from different regions traded at different values.