This was a problem a couple of months ago, and then it went away. It concerns the GUI only. It is a GUI issue; not a defrag issue.
Running XP (64) with 4 HDDs divided into a dozen partitions, I find that the boot drive USED SPACE and FREE SPACE displays "vibrate" as though the last 999,999 bytes are being processed very very fast. But it is effectively the equivalent of a hang or a freeze. The only way to abort is usually a Defraggler kill via Task Manager, and even that can be a bit sticky. The thing just wants to hang there with those two lines vibrating their numbers.
All the other partition defrags work fine. Only problem is that Defraggler WANTS to return to the boot partition when I restart Defraggler, as though it has a fascination for the one partition it can't handle.
In DOS mode?and therefore without the GUI?it works perfectly in all or any partition. Clearly the problem is entirely with the GUI.
I have no difficulty working around this, as per above, and I don't need any help. I am submitting this just so the devs know it is happening. Interesting that it would return after being OK for quite awhile. My Defraggler updates are always as soon as any new version comes out, so this was not immediately apparent this time around. Maybe the GUI breaks down a bit after a few scans; I wouldn't know.