avast 6 free and internet download manager(idm)

when i download virus by idm from mediafire.com,avast webshield do not abort connection of idm.because i can download it.but when i also download it(this virus from this link) by defauld download of firefox 4 or addon download them all of firefox then webshield aborted it immidiate.i want known webshield do not block idm when it download virus? link virus http://www.mediafire.com/?ekgg79xk5gd780b

Any download manager breaks the http stream into pieces to accelerate the download.
The pieces could “break” the detection of Web Shield.
It’s normal and there is nothing to do.
The full file will be detected at the end by ashQuick.exe (if you set so) or File Shield.