Changes

'''A quick way to test of the impact of antivirus software (AV) is to [http://bit.ly/1MU6eMa start starting Windows in safe mode], or [https://support.apple.com/en-us/HT201262 start starting Mac in safe mode].''' If your problem is gone with the operating system in safe mode, then the cause can be antivirus or some other software loading during the OS startup.

* '''*NOTE, testing by disabling antivirus using AV settings has proven over the years to not be a perfect or sufficient test. Sometimes , because sometimes AV setting changes do what they should, but often it does are noteffective. Therefore the only perfect test that can be fully trusted is OS in safe mode.''' * '''*NOTEIf you determine AV to be a problem, if then you altered must either disable the AV feature affecting Thunderbird file locations (typically by excluding the Thunderbird profile ), or change to a different AV program.'''** '''If you have altered Thunderbird to put your profile account data in a nonstandard file location or mail folders) then you MUST change set your antivirus software to exclude these nonstandard locations.'''