@Bisonium: As @Bibliothekarin said, we're probably not able to help you in any way, because there is a different system here in Germany. However, as the problem appears here, too, it is unlikely that it's typical to Swedish Tolinos. That, at least, should give you some leverage with German Telekom (telekom.de). Refer them to this thread and forum, if necessary
What irks me is the fact that you can use the same ebooks on other devices but not on your Tolino. That seems to imply that the books themselves are ok and that the delivery systems are working correctly, too.
Sorry to leave you hanging