Yes, indeed, CCleaner portable 6.06.10144 and older runs normally from a USB flash drive.
When a new version of CCleaner comes out, I always download the new portable version to the system C:\ drive and try it from there first, and if everything is fine, save it to a USB flash drive and use CCleaner portable from there normally. Since I couldn't run CCleaner portable from the C:\ drive, I didn't try again from the USB flash drive...
Thank you.