problem with Plesk if change the name of the server

[jonium]

I have a Win 2003 dedicated server with Plesk installed.
I need to change the name of the server (from start/settings/control panel/system/computer name/change), but when I do it i receive this error logging to Plesk panel:

ERROR: com_exception
<b>Source:</b> Microsoft OLE DB Provider for SQL Server<br/><b>Description:</b> [DBNETLIB][ConnectionOpen (Connect()).]SQL Server does not exist or access denied.

0: D:\Program Files\SWsoft\Plesk\admin\plib\common_func.php3:615
com->open(string 'Provider=SQLOLEDB.1;Initial Catalog=psa;Data Source=oldnameoftheserver\sqlexpress', string 'admin', string 'password')
1: D:\Program Files\SWsoft\Plesk\admin\plib\common_func.php3:615
reconnect()
2: D:\Program Files\SWsoft\Plesk\admin\plib\common_func.php3:590
db_connect()
3: D:\Program Files\SWsoft\Plesk\admin\auto_prepend\auth.php3:63

Where 'admin' and 'password' are the real account of Administrator...
It seems to be a config variable of Plesk that store the name of the server in order to find the mssql database.
Do you know how to change it?