I've searched the site and found a couple threads that come close to answering my question...but none quite hit the nail on the head:
I have a GY HM100u and am using 32 GB eFilm PRO SDHC cards to record to. Upon first filling up the cards and trying to delete all the files in cam/media mode, I noticed that it deleted the thumbnails but did not actually delete any of the media. I ended up deleting the files on my desktop, re-formatted the SD card in the camera, and found later the media was now being recorded to the CQAV folder on the card as opposed the BPAV folder.
So the question is, why isn't the "delete all" function on the camera working properly? What's the difference between the CQAV and the BPAV folders? And is chucking the "Private" folder on the desktop and reformatting the chip just something I'm going to have to get used to?
I just tried to replicate what you've been describing but found that the delete and delete all commands work fine for me.
I'm running firmware CAM 1.09, ARM 1.05 and EEPROM 052 and using SanDIsk 16GB Class 6 VideoHD cards.
Curiously I've never seen any kind of BPAV folder on a JVC camera, if I'm not completely mistaken those are used in the Sony EX1 etc. so what I can only assume happened is that you have used that card previously in an EX1 or similar camera without formatting. Could that be it?