De la Mancha just made a small bugfix update to dirtbox 3, which fixes a bug that appeared in Sonar 7 and sometimes in Ableton Live. The bug would mean that no audio could be heard when the dirtifier was on, or in some ring mod modes.
This version of Dirtbox from DeLaMancha is already version 3.0. It is a compression/distortion/modulation VST plug-in for Windows. Not longer as freeware but available now for a small price of 12 dollars.