Sharepoint WSS 3.0 backup stsadmin scheduled task command line fails

Hi

We have Sharepoint WSS 3.0 backup set as scheduled task using stsadmin command line batch file set to run full backup to the nas device on the network but it fails and just disappears off the screen without processing anything. Here is the file I have:

@echo off
cd\
cd "C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\BIN"
stsadm.exe -o backup -url http://sharepoint/ -directory "\\storage\NAS\Backup\Sharepoint" -BackupMethod
Full -percentage 5
exit

I have checked the permissions to the destinations and Administrator has full access. It is Netgear 314 ReadyNAs connected to our Active Directory.
If I open command prompt and run the command lines separately i.e.:
first running cd "C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\BIN"
then C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\BIN"
stsadm.exe -o backup -url http://sharepoint/ -directory "\\storage\NAS\Backup\Sharepoint" -BackupMethod
Full -percentage 5
it does run but still gives me an errors:
1. Error: Object SharePoint_Config_35300148-5f31-4d5a-b3ca-0f854f75678d failed in e
vent OnBackup. For more information, see the error log located in the backup dir
ectory.
2. SqlException: Cannot open backup device '\\storage\NAS\Backup\Sharepoint\spbr0002\0000000C.bak'. Operating system error 5(error not found).
BACKUP DATABASE is terminating abnormally.
3. Error: Object SharepointPortal failed in event OnBackup. For more information, see the
error log located in the backup directory.
4. SqlException: Cannot open backup device '\\storage\NAS\Backup\Sharepoint\spbr0002\0000000E.bak'. Operating system error 5(error not found).
BACKUP DATABASE is terminating abnormally.
5. Error: Object SharePoint_AdminContent_5f3dfeae-eb33-4cf6-a58e-41f31328ab76 faile
d in event OnBackup. For more information, see the error log located in the back
up directory.
6. SqlException: Cannot open backup device '\\storage\NAS\Backup\Sharepoint\spbr0002\00000010.bak'. Operating system error 5(error not found).
BACKUP DATABASE is terminating abnormally.
7. Error: Object 4bab9cf7-a32f-4915-a8f8-0c75498625c4 failed in event OnBackup. For
 more information, see the error log located in the backup directory.
        InvalidOperationException: System.UnauthorizedAccessException: Access to
 the path '\\storage\NAS\Backup\Sharepoint\spbr0002\4bab9cf7-a32f-49
15-a8f8-0c75498625c4' is denied.
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)

The thing is that if I run the same command but point it to local drive over the network on the same server then it completes fine.
Another thing is that it managed to create some files in \\storage\NAS\Backup\Sharepoint\spbr0002 folder.
And I don't have problems copying, moving or deleting the files to the destination. I have selected the inheritance of permissions to the child files and folders on the \\storage\NAS\Backup folder and replaced all permissions with the ones from \\storage\NAS\Backup. Just to let you know that Everyone has only Read&Execute permission to NAs as default. Not sure if I should remove that.
Also, the batch file seems not to go from one line to another as the window is gone so quickly. However, when I run commands one by one then it takes about a minute to go through.

Any ideas?
PS. I only want the full backup to run daily or full and differential scheme.

Regards,
Tom