Hello,

Can you please confirm if you have downloaded Firefox from http://getfirefox.com. Also, is it possible for you to confirm that the version of the file you downloaded is the same as the FTP version of the Firefox 25.01 https://ftp.mozilla.org/pub/mozilla.org/firefox/releases/25.0.1/linux-x86_64/en-US/firefox-25.0.1.tar.bz2 (this is the 64-bit version of Firefox).

Thank you

Hello gnittala, The problem seems to have resolved itself. For your edification below is what happened from the start of the problem. Thank you very much :) I downloaded firefox-25.0.1.tar.bz2 from: https://download.mozilla.org/?product=firefox-25.0.1&os=linux&lang=en-US I extracted it to /opt/firefox using sudo I am running Ubuntu 10.04 32bit Then: sudo rm /usr/bin/firefox sudo ln -s /opt/firefox/firefox /usr/bin/firefox This is my normal update procedure for Firefox and has been working for years. Anyway this time I got some error message in another language when I started Firefox. Sorry I did not grab a screen shot or record the message. Then I tried the same thing on an Ubuntu 10.04 64 bit box. Same thing. Then I downloaded the British tarball from: https://download.mozilla.org/?product=firefox-25.0.1&os=linux&lang=en-GB Success. Worked fine. Then today just for another try I re-installed the US version using the same steps as above. This time it worked fine. When I first start Firefox after the install I get the "Checking addons" message and it starts fine. Previously some error message. The puzzle is that I used the same downloaded file. I have been re-downloading it every day and using MD5Sum to check if the file has changed. No change. MD5Sum = 34f448f96de98e5b7f62edb21934d0ca Anyway whatever happened has fixed itself. Go figure. Thanks again.