There seems to be (and has been for some time) an apparent uproar about the Zune software on the Samsung Focus device over on the Microsoft forums. There appears to be an issue, which many are experiencing with ZunePass content and synchronised playlist.
During the remaining ten seconds of a song it will freeze for a moment or two, play the following second, lock-up once again and continue this loop until the media is finished. Both owners of installed microSD cards, and without have reported this.
Looking into the reports on the forum thread, people seem to be experiencing the stuttering playback issue in completely different circumstances - through the audio jack, via BlueTooth and the built-in speaker. Not only that, but there are more reports that have been posted about the Omnia 7 device that seems to stutter through playback also.
I have attempted to reproduce the problem folk are experiencing on my Omnia 7, but have failed to find anything - I have also been using it as an MP3 device for a month now through commuting and general use, and have never noticed this issue. [Edit: Our own Daniel Rubino has seen this on the Samsung Focus though, numerous times]
Should it be a Microsoft or Samsung fault, we do hope they are looked into as this could seriously impact a user's experience on WP7. Are you experiencing the same problem on your Samsung device?
Thanks Brian for the tip!