Need to check the logs in detail, but this looks as if your database file is messed up.
I wouldn't recommend stopping and restarting the server so often. That typically makes things worse instead of better. I'd recommend to start clean, I.e.:
Stop Server and Client.
Go to C:\ProgramData\Team MediaPortal and delete the whole MP2 Server and MP2 Client directories.
Restart Server, restart Client.
You will need to attach the Client to the server, but you will get a notification about that. Should be self explanatory.
Then re-add your MediaSource an let it import without stopping the server.
Then post logs here
I wouldn't recommend stopping and restarting the server so often. That typically makes things worse instead of better. I'd recommend to start clean, I.e.:
Stop Server and Client.
Go to C:\ProgramData\Team MediaPortal and delete the whole MP2 Server and MP2 Client directories.
Restart Server, restart Client.
You will need to attach the Client to the server, but you will get a notification about that. Should be self explanatory.
Then re-add your MediaSource an let it import without stopping the server.
Then post logs here