Very doubtful those are true Viruses.

I would suspect a false-positive from your Anti-Virus program; that happens from time to time immediately after a Firefox update.

Run a manual update for your A/V program and then run a scan of your drives, and see if that warning goes away.

You may be right. However, it is a great co-incidence, is it not, that I should download Firefox for the first time and find that, within 24 hours, the security of my internet banking has been compromised, while I find a record of these viruses in the Mozilla Firefox directory. I cannot, of course, try the demonstration you suggest, as the viruses have now been removed by the AV software.

I hope these viruses (if they exist) may have nothing to do with Firefox. But I feel you should be aware of the possibility that they might be related to my downloading the software. Afterall, these viruses (again, if they exist), appeared at the same time, and I don't think I downloaded any other software on that day. And something allowed someone to gain access to my internet banking the following day - though the AV scanner did find one other virus, albeit one which appears to have arrived later.

I have now removed all the viruses, and am scanning again to be sure.

All the best Paul

Paul, A/V programs look for patterns in code that look suspicious to the A/V application, but the A/V program will not flag files that are known to contain that pattern if the internal A/V detection files know those specific files are part of a valid application. We usually see postings about problems like you are having immediately after a Firefox update, because the users A/V program vendor was slow adding the new Firefox files to their database and slow in sending those updates to their users. We have seen repeated problems from a few A/V vendors over the years, usually the suspected problem goes away when the user forces an update manually thru the offending A/V program.

I can only guess that your A/V program flagged something in Firefox because it was a newly installed program, and it didn't expect it to be installed.

As long as you are downloading Firefox from a Mozilla download mirror website, the chances are slim to none that you will get a true virus as a result of downloading and installing Firefox. Which is why you should only download Firefox from an official Mozilla web page, like this: http://www.mozilla.com/en-US/firefox/firefox.html

Sorry, you had that problem.