An specific problem of runnig exe files is when AVAST does not allow to run DOS programs under a XP window (cmd window).
The AVAST does not run AutoIt executables (one of the best, or probably the best, macro runners under XP).
The solution of registry editing would not work on this. The question remains: why Norton AntiVirus, McAfee and AVG does not stop this executables and Avast does? ???