I am using Thunderbird 38.3.0. I am using Provider for Google Calendar 1.0.4. If I add an event from the web or my iPhone the date and time are correct in Thunderbird. However, if I add the event from Thunderbird, the date is correct but the time is 4 hours early. My time zone is Eastern US or GMT-5. I have thunderbird portable on a USB drive and when I copied that to my PC and added an appointment, all works fine. I also added an appointment to my "home" calendar and it added the entry correctly. This only messes up when I add an entry to a google calendar when I have copied and pasted the location into Thunderbird. It happens with all 3 calendars I share on only 1 of 4 machines. I have checked my PC and the time zone is correct on my PC. "Eastern Time Zone GMT -5. When I go to Google Calendar, it shows GMT-4 as Eastern Time and GMT-5 as Central Time. I have 3 calendars that I am sharing on 4 different machines and mine is the only one that has this problem. All are running the same OS and all are using 38.3 and Provider 1.0.4. Thunderbird portable works fine on my machine. Changing the time zone on my google calendar page doesn't impact adding calendar entries from the 3 good machines and it doesn't help my machine with is entering times 4 hours earlier than it should. Any ideas what might be going on would be most appreciated.