The only field that got wiped in my test was the full text field, and you have it set to get the value of:
ValidatedField("editnews_784","newsFULL")
but the field name is newsTEXT not newsFULL.
I don't think the validation would prevent the session variable from being saved. I'd need ftp access to debug that one. Are you sure it works when you don't have a failed validation first?