Everything was OK for many years when suddenly Thunderbird on Windows 10 stopped to work properly. It started asking to add security exceptions for every account installed immediately when opening it. I added all the exceptions (although they were a little bit strange, because in other computers with the same configuration everything was still working as usual) but with poor results and after a while Thunderbird crashes. I open it again, I add again the exceptions and again after a bad working it crashes. Then I made a backup of the profile and tried to reinstall it without solving the problem. The profile is still there and nothing is changed. I uninstalled it again, deleted manually the profile (both from AppData/Local and Roaming) and reinstalled it to have a new and clean profile but something is wrong again. I notice immediately that it seems not to connect to Mozilla's servers and when I try to add an account it doesn't complete the informations about imap and smtp (gmail !!!) because it cannot connect to the server. I tried then to use Thunderbird in a new Windows account (in the same computer) and everything was perfect. Not understanding what more to do and searching something on the web I eventually tried to run Thunderbird "as administrator" and finally IT WORKS WELL!! So, why now I have to run it as administrator to make it work? Can you help me please? I thank you all in advance.