ORA-04091 with table insert

Hi Group, Oracle 10G - This is my problem: There's a table containing a time series like date,val 1.1.08,2 2.1.08,1 3.1.08,4 5.1.08,-1 Now I need to advance this table in time, the new records come from a query so I have something like: insert into timeseriestable select date,val from timeseriesquery