Microsoft OLE DB Provider for ODBC Drivers error '80004005'
[Microsoft][ODBC Driver Manager] data source name not found and default driver not specified (sound like this in english)

Microsoft OLE DB Provider for ODBC Drivers error '80004005'
[Microsoft][ODBC Driver Manager] Specified driver could not be loaded due to system error 126

Microsoft OLE DB Provider for ODBC Drivers error '80004005'
[Microsoft][ODBC Driver Manager] Specified driver could not be loaded due to system error 5

This are the errors.

I try connecting to an Oracle db using SQLNet shipping with Oracle7.3
and its drivers (I tryed ver 1.0, ver 2.0 and ver 2.5 and none works)
SQLNet is installed on a PDC Win2000 srv and Active Directory and IIS5 as web srv.
The oracle utility ODBCTest run well and the connection is done but when i try to use the same dsn via web asp page the error occurs.
I tryed also to grant permissions to iusr_... (anonymous internet user)
to the file sqo32_73.dll and to all its directory (I hoped the cause was something regarding that) but not works anyway!
The three different errors derived cause I grant and then revoke the permissions decribed above (on a machine that is not a PDC returns system error 5 on a PDC returns system error 126)

On another machine win2000 srv with IIS5 it works well but it isn't a PDC and haven't Active Directory installed.

I'm becoming crazy solving it, thanks to Microsoft, Oracle and my ignorance of course! ;-)

It was really a permissions matter!
Not on file system but on registry!!
For some unknown cause, maybe a security update patch, the only users that can read the dsn entry in the registry was Administrors group.
So it was enough to add the anonymous internet user to the key of my dsn (IUSR_SERVERNAME) with permission 'read' checked and the connection via asp page go!
In other machines I found the user SYSTEM, CREATOR OWNER, Power Users group, and Users group and obviously all works well.

I found the solution in at this link:
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q306345

Moreover some tips can found in the Microsoft Knowledge Base article Q255084 and Q259959 (but not for this case!)

So, today my ignorance is decreased, thanks to Microsoft, Oracle and my perseverance of course! ;-)