Why WinCCRT resets all tags in PLC via OPCserver, when stops

[Alex3110]

When WinCC RT is terminated it resets all tag values in PLC via OPC server.
It’s very bad, as all setpoints and PID-gains in PLC are also reset.
On PC there are :
- WinXP Professional SP3 ;
- Simatic NET РС Software v.7.1 + SP5
- communication processor CP5613A2 ;
- OPC.Simatic.Net as OPC server ;
- “Simatic PC Station” is configured ;

What can we do ?

Thanks in advance.