Editing feature problem

Hi,

I have a problem with Viewer for Flex 3.3 Russian, EditWidget, ArcGIS Server for WG 10 sp5.

I can create new features, and I can update new feature' s geometry and attributes . But I couldn't edit old features created in ArcMap in geodatabase in some feature classes. My Flex Builder or Web application freeze and 2-3 minutes later I can see attribute form without attributes with labels Delete and Cancel only. Feature is selected but feature geometry is also without nodes.

I can edit only some features in another feature class.

And I can edit this feature service correctly in Silverlight Viewer for ArcGIS.

Any help please
Thanks