Freezing / can't read file after some minutes of playback

I use serviio several years and my experience with the program (installed on a win8.1 laptop and streaming on a Panasonic viera P50ST50 via a wired network) is excellent, except for a problem that occurred recently and I do not know how to deal with it.

At some point, after a Windows update I think, I noticed that movies (any movie) started freezing after some minutes of playback, and the message "Cannot read file" appeared every now and then. Playback does not completely stop - the movie starts and freezes every 2-5 secs. When I get to my laptop and just move the mouse, playback continues normally. But after 5 minutes or so the problem reappears. I tried "system restore", chose a point before the latest update and the problem disappeared. (Power management is always in Balanced mode with the same settings)

However, at a later time the problem reappeared. Meanwhile -of course- I had installed / uninstalled some programs.

Is there a way to deal with that problem other than restoring my whole system to an earlier point in time?

P.S. I use the latest serviio version. Is there a reason to perform the ffmpeg update? (http://wiki.serviio.org/doku.php?id=win_ffmpeg).

[DenyAll]

Do you know what changed after the restore point (Windows can tell you what software is being affected by the restoration)? Maybe a software conflict?
Is anything starting up/becoming active after 5 minutes (monitor your processes in Task Manager and monitor CPU usage)?
Also, what happens if you turn power management off (change the plan to disable all forms of sleep, or extend your sleep timer out to 60 minutes)?

P.S. I use the latest serviio version. Is there a reason to perform the ffmpeg update? (http://wiki.serviio.org/doku.php?id=win_ffmpeg).

No, not normally - there is no requirement to do so for Serviio on Windows.