Brand new Sansa Clip+ often restarts

I would first update the firmware to the newest, 01.02.18. That has a bug fix in it that may solve your issue. I would recommend manually updating  it though, instead of using the Updater. The simple instructions are in the firmware post linked to.

And don’t worry; updating the firmware, resetting or formatting won’t affect your warranty status.

Was this a “new” unit or a re-furbished one? Many here would like to find one given that it’s been discontinued for some time and there are limited ones on the market today, and it has many advantages over SanDisk’s current offerings, the Sport & Jam models.