Check the settings in Options > Privacy > Settings and see if the browser is set to clear cookies when it closes. You can keep cookies and still have no unwanted ones if you default to blocking cookies and then make exceptions to allow only those that you need, and do not clear cookies. Maybe Firefox is clearing out data when it restarts after the computer wakes up?

Make sure that you do not run Firefox in (permanent) Private Browsing mode.

• https://support.mozilla.org/kb/Private+Browsing

• Tools > Options > Privacy: Use custom settings for history
• Deselect: [ ] "Always use private browsing mode"

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do NOT click the Reset button on the Safe mode start window or otherwise make changes.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

If you use cleanup software like CCleaner then check the settings for the Firefox application.

If clearing cookies doesn't work then it is possible that the cookies.sqlite file that stores the cookies is corrupted.

Rename (or delete) cookies.sqlite (cookies.sqlite.old) and delete other present cookie files like cookies.sqlite-journal in the Firefox Profile Folder in case the file cookies.sqlite got corrupted.

• http://kb.mozillazine.org/Cookies
• https://support.mozilla.org/kb/Deleting+cookies

Thank you for your response. I do not have it set to clear cookies when it closes. There was a problem w/that in earlier versions & so what I did & still do, is to first check the box so I can get into the settings, then uncheck all of the options. I then uncheck the clear cookies & that's always taken care of the problem.

I have 3rd party cookies blocked & 1st part cookies set to prompt. (been doing that for years) I have "accept cookies from sites" checked w/"ask me every time"

Unfortunately, it doesn't always prompt cookies.  :-( I just went to my exceptions and two of the sites I'm on every day have NOTHING listed in exceptions. Yet, when I checked 'show cookies' they are listed there. Doesn't make any sense to me.  :-/

This only start AFTER I updated to 18.

My above reply was to finitarry. Apparently I was typing my response while cor-el was posting.  :-)

Thank you cor-el for your reponse.

I am not in private browsing. I don't currently use CCleaner or the like.

I will do the other two things you suggested & let you know what happened.

Note that setting the cookies to "ask me" may cause issues with setting an allow exception for a specific domain and this may block cookies from other sub domains.
We have seen this the Facebook where a cookie exception for www.facebook.com was created, but an exception for facebook.com was needed to include all facebook domains (Bug 783358).

Re: facebook. Several weeks ago I found a thread in this forum that said specific cookies needed to be manually entered into the exceptions. They were facebook.net, facebook.com & fbcdn.net. That has solved all of my facebook issues.

I went into exceptions & typed in the missing websites & will see what happens next time I close out my browser.