Default_get : Fields of _inherits ignored for default values

when you want to create a new case for inbound or outbound phone calls (crm & SRM -> phone calls -> inbound -> new incoming call) on a fresh system you get the following dump :

Release: 9.10
Codename: karmic
Operating System Release : 2.6.31-19-generic
Operating System Version : #56-Ubuntu SMP Thu Jan 28 01:26:53 UTC 2010
Operating System Architecture : 32bit
Operating System Locale : en_GB.UTF8
Python Version : 2.6.4
OpenERP-Client Version : 5.0.7
Last revision No. & ID :Bazaar Package not Found !Traceback (most recent call last):
  File "/usr/local/lib/python2.6/dist-packages/openerp-server/netsvc.py", line 244, in dispatch
    result = LocalService(service_name)(method, *params)
  File "/usr/local/lib/python2.6/dist-packages/openerp-server/netsvc.py", line 73, in __call__
    return getattr(self, method)(*params)
  File "/usr/local/lib/python2.6/dist-packages/openerp-server/service/web_services.py", line 576, in execute
    res = service.execute(db, uid, object, method, *args)
  File "/usr/local/lib/python2.6/dist-packages/openerp-server/osv/osv.py", line 58, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/usr/local/lib/python2.6/dist-packages/openerp-server/osv/osv.py", line 119, in execute
    res = pool.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/usr/local/lib/python2.6/dist-packages/openerp-server/osv/osv.py", line 111, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/usr/local/lib/python2.6/dist-packages/openerp-server/osv/orm.py", line 2141, in default_get
    if obj._columns[field2]._type in ('many2one', 'one2one'):
KeyError: 'date'

Server is at revision 5.0.7