volgens Colin Fraser.
Can we have a bit more information please, like version number, environment. What is your database, PostGreS, MySQL, MSSQL, Oracle? This is not a common error, so the more information you can provide us, the better the chance of resolving the issue. BTW, if you can, turn on Error Messages, go to Site Administration > Development > Debugging and switch to ALL: Show all.... There is often a number of additional error meassages that can help pinpoint an error. You may want to go directly to DEVELOPER: level, that gives additional messages, but it may not be helpful.