The problem started when I had to do a System Restore to get rid of a rogue program. When I next tried to open Thunderbird, I got 'Couldn't load XPCOM' error message. I tried reinstalling Thunderbird and it now opens, but all I get is the Home page. When I click on a folder, e.g. Inbox, nothing happens; similarly, when I click on Address Book or Write. The only way I can get to a folder is to right click and then open it in a new tab. When from here I try to reply to a message, again nothing happens. This started with Windows 8, but I have since moved to Windows 10, partly in the hope that this would solve the problem, but the situation remains the same.