DOS Protection Menu - USB keyboard

Unable to access the file scanning in XP dos mode on start-up using a USB keyboard.

Was unable to respond to requests for removal of a file as the keyboard would not function.

how do I disable this virus scanning tool?

It should disable itself automatically (it should run only once after you schedule it), doesn’t it behave this way ?
Could you please send me the file C:\Program Files\ALWIL Software\Avast4\Data\log\aswBoot.log ? (to peterka@asw.cz)

See also this thread: http://www.avast.com/forum/index.php?board=2;action=display;threadid=874