Database might be corrupted. I had a similar problem:
userid_wrdp2.wp_posts warning : Table is marked as crashed error : Checksum for key: 3 doesn’t match checksum for records error : Corrupt
Resolved it with my hosting provider.
solved it with my hosting provider.
Had a similar problem running 2.6. The database was corrupted:
userid_wrdp2.wp_posts warning : Table is marked as crashed error : Checksum for key: 3 doesn’t match checksum for records error : Corrupt
Check with your host provider. I had a similar problem runing version 2.6 and the database crashed. I logged into my Control Panel at my host and they had a way to check the MySQL database. Told the admin and they fixed the problem. Hope this helps.
Most likely your database crashed or it has some errors. Check with your hosting provider.
