So, for instance one of apps renamed itself to "Content on this profile might be inappropriate for those under a certain age" and displays that message (and "Stopped.") in a MessageBox when started. Its icon also changed (to a grey heart; another changed to a grey edit-pencil). It works again after reinstalling it though. And my VLC player app is now called "_".
Do you think my phone fell victim to a virus? I got the Kaspersky virus scanner installed and when doing a full scan it finds nothing. I guess it's probably just some bug.
Maybe someone else had the same problem?
Edit: it appears that moving apps from my phone to the SD card was causing the icon-problem. The icon of Firefox changed to some grey icon after doing so. It changed back to the proper icon after I restarted the device. Not sure if that was also causing the app-names problem and I think it's unlikely to have caused that soundcloud-app-problem.