Have Thunderbird Beta on this PC. Starting program begins 2-3-4+ minutes of hard drive light churning away. After program finally opens it will not download emails I know (from another source) to be on the server. When I click on Get Email, another 2-3-4 minutes of hard drive light activity before a modest 4K email will download. If I download & install the "regular" latest Thunderbird, will this overwrite the Beta install & cure the annoying sluggishness? It's been several months now of increasingly frustrating performance & I would like to have "familiar" Thunderbird back. I wish to do this without losing my address book's contents, obviously. I have "regular" Thunderbird as a portable install on a thumb drive for use with my sporting club's mailings, correspondence,etc., and it's as quick & clean as the Thunderbird that got replaced by the Beta version on the PC, the version (latest update, of course) that I wish to get back to. Suggestions?