This sounds like a problem with Sync.

Does this still happen if you temporarily unlink this computer (device)?

Do you mean to unlink which device, the "Nightly" PC ? All my devices are set to sleep at the end of the day, even the Tablet disconnects from the Wi-Fi network when the screen is Off (a new feature in Jelly Bean). Would it be the same as unlinking the devices? I think so. And it happens all the same. Does Sync saves something locally in each device that tells also the order of the items? Or does Firefox sort the items on the Bookmark Toolbar when it starts? BTW, to complete the picture:

• the "new" order of the items is not always the same, and it does not follow a specific sorting order (like alphabetic)
• The order changes only once, then it stays the same. Only when I reorder the items it happens again the next day.

I am having problems with syncing my Desktop Firefox, which I have had for years and really like the set out etc.

I have an Ebook 1340, this runs on Jellybean android but is not allied to Windows. It works perfectly on my WIFI. I have downloaded Firefox on to this and have tried to sync all, to no avail. My android comes up with all the necessary sync numbers, I then add them to my desktop as requested. My android then says "awaiting other device" and it just goes round and round. Never transferring. I can use Google as my website, but prefer Mozilla. My model number is WM8850-mid, Android version 4.1.1. Kernel version 3.0.8 Build No. 4.1.1 JB Ver1.3.0-20130131.033909

Can you help?