2012R2 server System writer missing in the vssadmin list writers

Hi,

I have some problem with a brand new 2012R2 standard server.

we were able to backup the server from the beginning without problems with the built-in windows backup application.

After installing Solarwinds and SQL server on it, now we have this error in the event logs if we try to backup system state:

The operation ended before completion. Detailed error: The system writer is not found in the backup.

If I check the VSSAdmin list writers, system writer is missing.

We also have this error in the event logs :

I did not find anything on the AddWin32ServiceFiles: EnumServicesStatusEx API... and the problem for the system writer seems to start from this error.

Anyone have an idea ?

thanks

Benoit