Ideas Wanted

So, um, yesterday Firefox was working fine. I swear. Today, however, I am required to sign in to every site. Even if I check the box to remember me, if I close my browser and re-open, I have to sign in again.

I’ve cleared my history (including cookies), because the Internet told me to. I disabled all of my plug-ins (yes, all of them). I upgraded to 3.5.4. Nothing has worked.

It is driving me crazy. Crazy, I tell you! (And I keep forgetting that I have this problem and continue to close my browser, even though I know just leaving it open for the rest of the day would “solve” this problem. Grr.)