about return result correctly for executing twice t-sql

I found this T-sql need to be executed twice for correct result since upgrading from sql2000 to sql2008.
Table structure:
CREATE TABLE [dbo].[Cname1](
[no] [int] NOT NULL,
[country_no] [char](5) NOT NULL collation SQL_1xCompat_CP850_CI_AS,
[CCoName1] [char](62) NULL collation SQL_1xCompat_CP850_CI_AS
) ON [PRIMARY]

Index:
index_name index_description index_keys
CCoName1_ind clustered, unique located on PRIMARY CCoName1, no
duns_no_ind nonclustered, unique located on PRIMARY no(-)
The T-Sql:
select no,CCoName1 from cname1 where (country_no='156' or country_no='-156') and cconame1>='content'
I try to rebulid index many times and it was of no effect.
Pls give me some suggestions
Thanks.