how do I stop antivirus from opening every time I download?

I use avast! 4.8 home edition, VPS file version 080407-0 on a Dell dimension 3000 with Windows XP sp2, and I also use Firefox rather than IE. This may be a simple question, but I can’t for the life of me figure it out. Every time I download something from the Internet, the avast! antivirus opens and starts its memory test. This is very tedious, as it does it even when I download a .JPG and I download things rather often. It did not do this with IE, but I like Firefox SO much better that I don’t want to give it up. How can I make it so the antivirus doesn’t open when I DL something?
PS - I am not very computer savvy, so bear with me

Probably you have set ashavast.exe into your download manager settings and you should point it to ashQuick.exe.

Using asQuick is useless for download managers ever since we got Web Shield which does the same transaprently.

If it comes through the http protocol… otherwise it won’t be scanned (like from ftp).

Thats why there is Standard Shield… HTTP scanning is important only because certain elements are rendered directly in browser without caching to disk. FTP engines don’t render anything, just transfer bits.