Aggregator deleted feed magicaly reappears

I have added some feeds. One of them is:
http://www.minedu.gov.gr/component/option,com_ninjarsssyndicator/feed_id...

When cron runs gives an error:

PDOException: SQLSTATE[22001]: String data, right truncated: 1406 Data too long for column 'link' at row 1: INSERT INTO {aggregator_item} (title, link, author, description, guid, timestamp, fid) VALUES ... etc

I tried to delete this feed, BUT every time cron runs it reappears without title and having the url and link fields in the aggregator_feed table with values (the correct ones).
I have deleted the record from the aggregator_feed table, but it reappears (with the same fid!) when cron runs.