Robyer, I've tried both changing password (it didn't help) and this advice how to delete deviceID before, but I didn't manage :-(. I open Database Editor, but I'm not able to find „key DeviceID in branch Settings/<account's internal name>“. In Settings, there are many many things, but nothing named DeviceID or account's internal name.
There are many things which seem not to have any relation among them. Names of contacts, things like AutoBackups, CList or Known Modules, all mixed together. Among all these things are Facebook_1 and Facebook_1]. Should I delete these two? I'm not sure...