There's a bug when doing the analysis on heavily fragmented drives. I had just received a new work laptop, and the D:\ drive had 32GB of stuff that Disk Cleanup could, well, clean up. After that, I went to defrag the drive, and it came back with 106% fragmentation. This occurred using the latest version (v1.11.148). See screen below:
Obviously, the math is wrong in calculating how fragmented a drive really is. There's not an upperbound, it would appear.
Thanks,
~Sark