Hi,
1) Could you please post whole error message you are getting with exact steps and version of Kentico
CMS so we can try reproducing this problem?
2) It seems that there is some kind of inconsistence in the DB - have you created any custom code or made any changes in DB directly? Have you tried to create the culture version of the document(s) in CMS Desk and then delete them again?
Best regards,
Juraj Ondrus