[squidsk]

A quick guess would be someone/something has played around with the autoincrement postid value for the post table.

To check this issue the following two mysql commands:

select max(postid) from bocetapost

and

SELECT AUTO_INCREMENT
FROM information_schema.TABLES
WHERE TABLE_SCHEMA = "DATABASE NAME"
AND TABLE_NAME = "bocetapost"

Note: Don't forget for the second query to change the db name to the one for your db.

If the second number is less than or equal to the first, take note of the postid from the first and run the following query:

ALTER TABLE bocetapost AUTO_INCREMENT = postid + 1;