SMON: Restarting fast_start parallel rollback

 hi I have done following in my database

1) insert the data in table --around 29460627 rows ( insert  test into select * from test1)

2) after 4 hours we are killed that  insert session (due to time and archivelog genaration)

3) then truncate that test table

4)shut DB and startup the DB with noarchivelog mode

5)  im getting alert log error

        SMON: Restarting fast_start parallel rollback
Fri Jul  2 11:36:43 2010
SMON: Restarting fast_start parallel rollback
Fri Jul  2 11:40:43 2010
SMON: Restarting fast_start parallel rollback
Fri Jul  2 11:44:43 2010
SMON: Restarting fast_start parallel rollback
Fri Jul  2 11:48:44 2010
SMON: Restarting fast_start parallel rollback
Fri Jul  2 11:52:44 2010
SMON: Restarting fast_start parallel rollback