You're right. I didn't know the instructions about how to upload logs. :sorry: Now I'll do it correctly.
I've attached the logs. The file Mediaportal.log clearly shows the problem. However, I'm unable to infere a solution from it. Does anyone know what the problem could be?
Well, nobody seems to know what the problem is. Neither do me. However, the problem is solved now. I've upgraded MP to version 1.1.1 "et voila". Problem solved! I uninstalled everything related to MP (MP 1.1.0, MP Streamed Skin, .NET and MySQL DBMS). Then, I installed everything again (MP version 1.1.1 instead of 1.1.0). Since then (two weeks ago), no error has come up.
As always, I post here the solution (just upgrade version?) for others in my situation. Thanks.