With Trac 0.12 and PostgreSQL there is a datatype issue. For example when trying to create a TestPlan? Pg won't store it because the value for the "time" column does not fit into the integer type range.
As a work-around I changed the data type on my local instance using "alter table testplan alter column time type bigint;" but I guess resorting to bigint is not the nicest resolution.
generate those too large values
INSERT INTO testplan (id,catid,page_name,name,author,time,contains_all,freeze_tc_versions) VALUES (E'42',E'43',E'TC_TT43',E'testtestplan',E'mkroell',1357563642946958,1,0)