ru running xp? if so u will need to turn ur system restore off and then run the anti virus and delete it that way.
also stop the process first (ctrl, alt and del, opens task manager, then look for the .exe and right click and end process)
this should allow u to delete it. Make sure ur system restore is off.
use trend and delete it, then remember to turn ur system restore back on.
I dont know why avast isnt finding it.