Overwrite does not overwrite all files

Hi,

Win XP/CC 1.40.520/IE6 - CC with 1 pass overwrite.

With CC set to 1 pass overwrite, it does not appear to overwrite all or even the majority of the deleted files.

Looking at the results with Recuva in last modified date order, there are a few dozen files with the name modifed to a random capital letter, such as LLLLLLLL.LL. Some of these don't have a defined path, some are from temp internet files. They all seem to be overwritten as I can't make head or tail of any I recover.

The rest of the files deleted in the same CC session keep their file names, many coming from temp internet files. Many of these are recoverable, not overwritten at all.

Why are the majority of the deleted and 'overwritten' files still recoverable?

Rgds.