Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

I always place my XP powered PC in hibernate mode at the end of the day. After posting my question re no Privacy pane, I decided to do a full cold boot of my PC. After it came back up, tried Options/Privacy tab and Privacy pane picks reappeared. Truly a mystery because this has never happened before.