This sort of string of errors is usually an indication that ePO can't talk to its SQL database. Before anything else, check that the SQL server is running, the DB is availabel, and that the credentials specified in ePO's config page are correct. (This sort of error is quite common when the account used by ePO to access SQL has its password changed - it needs to be updated in the config page.) Also check the orion.log for any errors.
Rebuilding should hopefully not be necessary