Hi Stefan
For this you can use the SAPGUI Stop & Restart on command line.(These commands are used in Windows based system)
1. To kill the SAP logon pad "taskkill /IM saplogon.exe /F"
2. To start the SAP Logon pad "start SAPLogon"
And you can use find the ActiveX components in the "Security Guide SAP GUI for Windows.pdf" http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/3099a575-9cf4-2a10-9492-9838706b9262?overridelayout=true
Thanks & Regards
Sriram