You can try not to use Delete browsing, search and download history on Firefox to clear the cookies, but to let all cookies expire when you close Firefox and make an allow exception for that site. Using Clear Recent History is all or nothing.

I have the same trouble as Jinx999. The combination of new privacy features in Adobe Flash Player 10.3 and the privacy settings I use in Firefox 4 clears ALL my Flash cookies (LSOs), even those from other browsers and stand-alone games.

Adobe says that Flash Player 10.3 fixes "critical vulnerabilities", so going back to 10.2 is not the best solution.

Is there some way to limit/manage the wholesale clearing of Flash cookies using the Firefox 4 - Flash Player 10.3 combination?

I am having a problem where my flash game saves are deleting themselves on their own. I don't even have to clear browsing history, and I do not have any cleaning software installed. I have set storage to unlimited and that worked for a few days but I loaded a game this evening and my save file was gone and the storage had been reset to 100kB. I haven't touched anything, haven't deleted anything. It's infuriating.

I have managed to solve it. I downloaded an add on called "BetterPrivacy" that was originally designed to delete LSOs. It's possible to designate some folders as protected, so you can avoid deleting the LSOs in them. The interface isn't entirely intuitive so I'd suggest backing up any saved games you want to keep before experimenting.

I also deleted my desired LSOs once, I suspect during a cleaning procedure, but I'm not sure exactly what I did.