The latest versions of Microsoft Movie Maker does not support saving to the previously used MSWMM format, only the new WLMP.
Sp there really does not exist any way how you could ever convert wlmp to mswmm. You will have to re-create the project in Vista version of Movie Maker from the original source data (video or pictures).
This conversion entry was verified by us and conversion was flagged as wrong or not possible.
Usually this happens when the conversion would try to convert different types of data between each other, such as audio to image, or it is not possible because incompatibility between programs, caused by closed file formats, very limited support etc.
If you find entry that you feel is flagged as bad wrongly, please tell us in the discussion below with as much as information as possible so we can fix it.