Why does it repeatedly lose my Profile?
This happens on both my Laptop and my Netbook:
On a completely random basis, Firefox will lose my pinned tabs. So far as I can tell, it keeps my bookmarks and my add-ons (although it's hard to remember all of them).
Even though I have the options set to "remember tabs from last time", it not only loses the pinned tabs, but non-pinned tabs that were left open as well. I'm getting a little frustrated having to restructure my tab arrangement once every 2 or 3 weeks.
And, yes; I've already followed the instructions for profiles...that doesn't seem to be the problem. And, yes; "remember tabs from last time" is STILL checked even after they've all been lost.
Opaite Mbohovái (1)
If you use cleanup software like CCleaner then check the settings for the Firefox application.
App (pinned) tabs and Tab Groups (Panorama) are stored as part of the session data in the file sessionstore.js in the Firefox profile folder.
Make sure that you do not use "Clear Recent History" to clear the "Browsing History" when Firefox is closed because that prevails and prevents Firefox from opening tabs from the previous session.