Surely, same reason. WinCDEmu is not based on a complex virtual SCSI controller and returns STATUS_NOT_SUPPORTED for all SCSI-related requests. I suppose, it is quite a rare case from the filter developers’ point of view, and both filters completely do not expect such situation. WinCDEmu itself does not modify other driver’s code or data. That way, a situation when an unexpected set of valid parameters crashes such a filter, is a bug of this filter. You can try posting crash dumps to pxhelp20.sys driver developers, maybe this will help them pointing out the problem.