Well, thousands of users do not have that problem, or as you suggest, they wouldn't use X-Notifier. Have you tried uninstalling X-Notifier, restarting Firefox, and reinstalling X-Notifier?
Otherwise, it's possible there is a conflict with another browser extension. To troubleshoot you would disable ALL your other browser extensions, then restart Firefox. Add your X-Notifier accounts, then close Firefox and restart it to see if the accounts are still there. If they are, then you'll have to re-enable the other extensions one at a time and restart Firefox each time and check X-Notifier for the accounts. Sometimes, the other extensions will then 'play nice' and not conflict... but usually you'll find one that causes a conflict (which is resulting in your loss of X-Notifier accounts).
If those suggestions don't work, come back and let the rest of us know.
(I'm just another X-Notifier user, helping out in the forum.)
Conflicts
Well, thousands of users do not have that problem, or as you suggest, they wouldn't use X-Notifier.
Have you tried uninstalling X-Notifier, restarting Firefox, and reinstalling X-Notifier?
Otherwise, it's possible there is a conflict with another browser extension. To troubleshoot you would disable ALL your other browser extensions, then restart Firefox. Add your X-Notifier accounts, then close Firefox and restart it to see if the accounts are still there. If they are, then you'll have to re-enable the other extensions one at a time and restart Firefox each time and check X-Notifier for the accounts. Sometimes, the other extensions will then 'play nice' and not conflict... but usually you'll find one that causes a conflict (which is resulting in your loss of X-Notifier accounts).
If those suggestions don't work, come back and let the rest of us know.
(I'm just another X-Notifier user, helping out in the forum.)