I don't know how Firefox knows how to fire up your AV scanner. Are you getting an error message?

Usually your virus software will scan anything saved to the hard drive without Firefox having to invoke it. Unless your downloads folder is excluded from AVG scanning or you have turned off real-time protection.

If you want to test whether AVG is on the job, you can download the "EICAR" test file: http://www.eicar.org/anti_virus_test_file.htm (scroll way down to the red warning above the download links, then right-click and use Save Link As)

Note: the EICAR file is not a real virus, it is an industry standard test to make sure your scanner is running.

Sorry, but I am not going to to try that, just need a update for Firefox4 to link to AVG, when I download a file it is happy, but when I logged off, an do a full scan it finds over 20 files, so it is either Firefox or AVG, I am running Win7 64bit, also Win7 Firewall, AVG updated every day, the Laptop is defrag daily, I am from the old Dos 6.0 and win 3.1, school

Are you saying that 20 files you downloaded were reported as malware in a manual scan, but not in real time? That's very serious.

But you might be seeing other threats that are not processed through downloads, and therefore do not integrate with scanning. For example, AVG might alert on scripts in your browser cache or tracking cookies.

Is there an easy way to post a list what your scan is turning up?

Meanwhile, back to your question:

I'm still not sure how Firefox knows about your virus scanner, probably connects with Security Center somehow...

I saw a thread on the AVG forums about a workaround. It involves installing the "Download Status Bar" add-on and then using its virus scan option. See: http://forums.avg.com/us-en/avg-free-forum?sec=thread&act=show&id=82321#post_82321