Do you close all open tabs before closing Firefox?

Firefox stores cookies used in tabs that are currently open in the sessionstore.js file as part of saved session data, so those cookies will be restored if Firefox is closed without first closing these tabs.

You can set browser.sessionstore.privacy_level to 2 (never) or 1 (non-HTTPS) on the about:config page to disable saving cookies via session restore in the sessionstore.js file. The browser.sessionstore.privacy_level_deferred pref is used when you do not reopen the previous session automatically via "Show my windows and tabs from last time" and uses the same values.

• http://kb.mozillazine.org/browser.sessionstore.privacy_level

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

Do you close out of Firefox using the "X" button on the upper right corner of the window? Sometimes that method shuts down Firefox before it completes its data clearance. Try using either of these methods to exit Firefox to see whether that makes any difference:

• "3-bar" menu button > "power" button
• (menu bar) File > Exit

Unrelated to that, there was a security patch for Adobe Reader/Acrobat XI last month that you can install using the Help menu inside your Adobe product to Check for Updates, or this page: http://www.adobe.com/devnet-docs/acrobatetk/tools/ReleaseNotes/11/11.0.15.html

Hopefully that will also clear up the strange situation of your Firefox having two older versions of the Adobe Acrobat plugin.

I changed the privacy level to 2. Also changed resume from crash to false. Seems to have done the trick. I'll keep my eye on this. Thanks for your help.