We need to get vpxd.log to dig further. The vpxd.log file is located at "C:\ProgramData\VMware\VMware Virtual Center\Logs" on your vCenter server.
---> As I said before, I don't have an vpxd.log in this folder. I've searched for it, but didn't find it anywhere on my vCenter server...
1) Verify that the configuration of the ODBC Data Source (DSN) used for connection to the database for vCenter Server is correct.
----> The VMWare vCenter DSN Configuration uses the "localhost\VIM_SQLEXP" Server.
----> The Integrated Windows authentication is used.
----> Connect to SQL Server to obtain default settings for the options is set.
----> Change the default database to: VIM_VCDB
----> Mirror server is empty. (USE ANSI quoted identifiers and nulls,paddings and warnings is set.
----> Peform translation for character data is set.
----> TESTS COMPLETED SUCCESSFULLY
2) Verify the VMware VirtualCenter Service is running with the proper credentials
----> The service starts wirth ".\Administrator" as user and the PW.
3) Verify there is enough free disk space on the vCenter Server
---> We have over 100GB free disk space.
4) Verify that ports 902, 80, 8080, 8433 and 443 are not being used by any other application
---> The WWW-Publishing service blocked one of these Ports, but as I said in my first post, the service is deactivated.