Does it definitely have a $ sign in the name? $ in a file name usually suggests an open or temporary file. Can you give us the full name of the file so we can see what info we can find on it?

Over the last couple of scans the following 4 files have appeared

$DMVB.AVG
$EMVB.AVG
$FMVB.AVG
$GMVB.AVG

Each file is exactly 17.7MB