Mad Nightmare,
I had Avast installed since 2006. Dbp since 2004. Both worked along until the last avast program update, a few days ago, Jan 2011.
I upgraded to win7 almost a year ago.
You are right, it can work along without trouble.
As a scientist myself, experimentally I can tell that it was the only factor that made DBP fail. Since many dbp users had the same problem with the same solution, there is a common point.
You can not assure that two programs on the same OS will work identical. There are drivers, hardware, many factors that create different conditions.
May the 3d force B with U