php mssql_query() fail without any error and only when selecting a particular table

I don't understand why this piece of code miserably fails. The first pass of the for() loop works fine but in the second pass mssql_query() fails, no errors are reported and the program just die.

for($i=0; $i <2; $i++){
       $query = "SELECT * FROM Viaggio ";
       $result = mssql_query($query, $link) or die("query fallita:".msql_error());
          if( mssql_num_rows($result) ){
             while($row = mssql_fetch_array($result, MSSQL_ASSOC)){
                echo 'blablablabla' . $row[some_index] . 'blabla';
             }
          }
    }

I don't know why this happen, It's works with all the other tables in my database except for Viaggio. This is the CREATE TABLE query directly from msSQL:

SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [dbo].[Viaggio](
 [codViaggio] [bigint] IDENTITY(0,1) NOT NULL,
 [data] [smalldatetime] NOT NULL,
 [oraArrivo]  AS ([data]+[durata]),
 [corsaExpress] [bit] NOT NULL,
 [durata] [time](7) NOT NULL,
 [fascia] [nvarchar](50) NOT NULL,
 [distanza] [char](3) NOT NULL,
 [nave] [nvarchar](50) NOT NULL,
 [partenza] [nvarchar](50) NOT NULL,
 [arrivo] [nvarchar](50) NOT NULL,
 CONSTRAINT [PK_Viaggio] PRIMARY KEY CLUSTERED 
(
 [codViaggio] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

ALTER TABLE [dbo].[Viaggio]  WITH CHECK ADD  CONSTRAINT [FK_Viaggio_Nave] FOREIGN KEY([nave])
REFERENCES [dbo].[Nave] ([nome])
ON UPDATE CASCADE
GO

ALTER TABLE [dbo].[Viaggio] CHECK CONSTRAINT [FK_Viaggio_Nave]
GO

ALTER TABLE [dbo].[Viaggio]  WITH CHECK ADD  CONSTRAINT [FK_Viaggio_Rotta] FOREIGN KEY([partenza], [arrivo])
REFERENCES [dbo].[Rotta] ([pPartenza], [pArrivo])
ON UPDATE CASCADE
ON DELETE CASCADE
GO

ALTER TABLE [dbo].[Viaggio] CHECK CONSTRAINT [FK_Viaggio_Rotta]
GO

ALTER TABLE [dbo].[Viaggio]  WITH NOCHECK ADD  CONSTRAINT [FK_Viaggio_Tariffa] FOREIGN KEY([fascia], [distanza])
REFERENCES [dbo].[Tariffa] ([fascia], [distanza])
ON UPDATE CASCADE
GO

ALTER TABLE [dbo].[Viaggio] CHECK CONSTRAINT [FK_Viaggio_Tariffa]
GO

Thank you very much

[EDIT] I just tried to use mssql_free_result() but also this function crash the program.