Fragments in block view, but no fragmented files

[thany]

This is happening with Defraggler 1.08 on Vista x64.

 

I sometimes end up with a volume that still shows some red in the block view, but no fragmented files are reported. Not even after another analysis. If I click one of of those red blocks, one of three different things may happen:

 

1. I see the $MFT file (or another $-file) being fragmented. This is normal, but I guess Defraggler cannot defragment such files.
   
2. I see a fragmented directory (that's the directory-entry on the FS, not files inside such a directory). I know Defraggler can technically defragment directories, but it seems that it doesn't (completely/correctly) happen.
   
3. No fragmented files under a red block. That is just too weird.
   

I also took the time to do a "chkdsk /v" on this volume, but it came out totally clean.

 

Any ideas why this may be happening?

Perhaps bugs?