Win 10. Multiple email accounts, some gmail plus others. I had TB 115 something (it's uninstalled so not available to see). I run Firefox without issues. TB went completely haywire, all email accounts disappeared, nothing worked (second time this year) but recovering was proving too difficult and I'd already spent a whole day on it. I decided to uninstall and install a fresh copy. First I copied the single profile to an external drive. Then I uninstalled TB. Then I ran Ccleaner to tidy up the remaining TB cache and other remnants, also cleaned the registry. I downloaded a new copy from Mozilla's site, ran the install file, The install dialog box offers the same install location as the previous location, same user. Upon clicking install, the dialog box disappears and nothing happens. I've tried this more than ten times now, including fresh downloads from Mozilla. The dialog box offers an alternative user as Administrator but that won't work because I don't actually have the administrator account set up with a password, and TB demands the password. I do not want to open a new user account just for TB. Any suggestions for working round this will be gratefully received.