All the issues I've seen look like MySQL performance issues to me. Pretty much any time you see the "Database Error" page, it means that MySQL is eviscerating itself. Could be not enough RAM, could be improperly configured cache settings. Tuning MySQL is a black art. It's extremely difficult to get right, and forums are notoriously difficult for database servers because of their nature (high write volume, frequent cache invalidation because of updates).
His: 2013 ///M3 - Interlagos Blue Black M-DCT
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