Thanks for the info and discussion but I am not actually opening the file, just virus scanning.
Internet Download Manager 4.x has a parameter for a virus scanner for example, with Norton antivirus:
C:\Directory\Norton\NAV32.EXE [file] /S
This scans the file immediately after it is downloaded. I still don't see a similiar command in Avast but then often times I miss the obvious.
Again Thanks