Problem saving settings

[lukaszhandy]

Hi
When I try to save my user settings, I get the error:
SQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or update a parent row: a foreign key constraint fails (groupoffice.tasks_tasklist, CONSTRAINT tasks_tasklist_ibfk2 FOREIGN KEY (createdBy) REFERENCES core_user (id))

Today I installed the groupoffice update: amd64 (6.6.64-sixsix, 6.6.71-sixsix)

Regards