this is code:
Dim strSQL As String
Dim strCon As String
strCon = "Data Source=NITHI;Initial Catalog=master;Integrated Security=True"
Dim cmdBackup As SqlClient.SqlCommand = New SqlClient.SqlCommand


Cursor = Cursors.WaitCursor
Try
strSQL = "BACKUP DATABASE Northwind "
strSQL &= "TO DISK = 'G:\mybackup.bak' "
strSQL &= "WITH FORMAT, "
strSQL &= "NAME = 'myBackup'"
cmdBackup.Connection = conn

cmdBackup.CommandText = strSQL
cmdBackup.ExecuteNonQuery()
MsgBox("finish")
Catch ex As Exception
MsgBox("Error")
End Try


if i back up to G:\ ,it is Ok
but when i backup to C:\ ,it's not OK
what happen?

(about my computer)
i have 2 harddisk
partition G is slave harddisk
and partition C is master harddisk


this is error: "Cannot open backup device 'C:\mybackup.bak'. Operating system error 5(error not found).
BACKUP DATABASE is terminating abnormally."


please help me

The SQL user probably doesn't have permissions to access "C:" drive.

Without access to the machine, it's impossible to say. It could be an ACL, as Chris suggested. It could be filespace. It could be any number of things. You'll have to put on your debugging hat.

and i can only restore form C:\program file\microsoft sql server\mssql1\mssql\backup\....

what's happen?

Mail me your server and I'll tell you. Otherwise, you're going to have to research the error.

Bubble wrap the hard drives first though

Probably a very good idea, as Chris suggests.

FYI, the root directory on the CEE drive (aka C:\) is protected in some versions of Windows, particularly server installations. That protection applies to the folder, not the drive. So, being able to write a file to a particular folder, buried deep under the root, doesn't say anything about whether or not you're allowed to write to the root folder itself. An ACL (that's access control list, part of NTFS permissions) may be preventing the user account the SQL backup is running under from writing here.

To see whether or not that's the problem, debugging 101 suggests you try using code to write a small (or even empty) file to the root folder in C:\. If that works, figure out what account the backup is running under (NETWORK SERVICE?) and test their privs to the root folder on CEE.

I'm guessing that's the problem, but there are many possible causes. If you're being paid to develop software, you really need to understand the very basics and figure out how to debug the programs you write.

first step ,what should i do?

Read the manual?

i don't have manual.
i don't have book about SQL server
i only have Book about vb.net with SQL server

i have to know use SQL server
my english isn't good

i'm sorry if you don't understand what i say

It's not a SQL Server error. It's with Windows, or your network. Look into the NTFS permissions on C:\.

about my program.

if my problem happen by windows.

It's difficult for write program.

of cause, my program can't use backup and restore cause
i restore only from c:\.....\sql server\backup
but i can only backup to G:\..

oh..! my sql server is version preview.

If SQL Server is able to read and write backups to other locations, like the G drive and Program Files under C, then the problem isn't with SQL. It doesn't matter whether you have the time limited preview or enterprise edition. Windows isn't giving SQL permission to write to the root folder of the C drive. You can either put your backup somewhere else, or grant permission.

install new version of windows XP?

No, it will be the same as the current version you have. The answer was already given, I don't understand why you refuse to take advantage of it. But you can do all kinds of things that don't address the problem, and still not solve it.