I've used TreePie on several machines and found one that does not work very well.
When I use it to visualize the C: drive on my new Windows 7 computer, x86-64 edition, (230 GB drive, with 150 GB free space), it creates a pretty confused result. Most of the folders display red, and the name of the folders when you hover over changes, but not in any correlation with the displayed pie chart. The sizes are also all over the map.
TreePie 1.2 has no problem with the C: drive. Also, TreePie 1.3 works fine on my old Windows XP machine, and on a smaller subset of the C: drive on the Win7/64 machine.
Look quite wrong. I hope to fix this soon