ORA-01013 - when doing large delete via ADO

Hi,
I'm doing a (very?) large delete from an Oracle database table, basically the table has about 650,000 rows that I need to delete (out of 1,300,000 rows in total). Every time I run this after a while I get a run time error with:

'ORA-01013 user requested cancel of current operation'


Below is a code sample:

cSQL = "DELETE FROM aircom." & rDel.Fields(0) & " WHERE projectno=" & iProject(sLoop)
dbOpen.Execute (cSQL)
'


any ideas on this one?

I'm using VB6 with ADO 2.7 and oracle 8.1.7

any help greatly appreciated

cheers

john