Wiedergabe plötzlich in doppelter Geschwindigkeit

Thank you very much for your answer. In fact, after setting the audio hardware preferences to "no input" the issue described above has not occurred any more, so I think it's resolved.

Thank you for your answer.

For you and others here is my English translation of my post (although probably not perfect):

"In Premiere Elements on Windows 10, it happens again and again that the preview video is played back wirth double speed while the audio playback is saccadic. That happens when the .prel file remains open an the program is minimized without using it for a few hours, also after wakening the computer from sleep mode ("save energy"). In the program I could not find any setting to fix that issue, closing and reopening the program included. The only way to fix the issue was to shut down and restart the whole computer. Is there any other way to fix that issue?"

The video files are in 4k-50 fps, H..264 codec, from an intern M.2 SSD drive, originally imported from my video camera. In Premiere Elements they work without any problem except in the special case described above. Processor i9-9900, 64 GB RAM.. There is no problem in the files as they work well except in the case described above."