Hi,
I've always used CCleaner to securely delete Sandboxie's contents using the path:
C:\Sandbox\Username\*.*
This has worked fine up until a couple of (CCleaner) versions back. Lately when I delete the sandbox with CCleaner, I'm left with the sandbox name subfolder:
Eg: C:\Sandbox\Username\DefaultBox
The contents are erased but the folder remains, which I then have to remove manually using SB. Not a big problem I know, just reporting .