It f*cked up all saved tabs. Second time. I haven't been making backups too often due to info from forums that previous version is free from this problem. The last version came without any wornings and deleted all tabs.
Unfortunatly the method, that was mentioned in commets.
If you use it, everytime make a backup via html doc.
Now I have to go - I need to get through the entire history for at least a week. F************ck!
F*ck the devs.