Ok I am still having problems.
I have a fat 40gig PS3 with CFW 3.55 (from cobra-usb.com), a cobra usb with FW 4.0. and Cobra USB Manager 4.0.
I have the folder structure on my external HDD as follows
dev_usb2\games\BLUS30772\ (then in that folder I have folders PS3_GAME and PS3_UPDATE and file PS3_DISC.SFB)
I plug my Western Digital 1TB HDD (formatted to FAT32 by Fat32FormatterEN) into the second USB port (with the Cobra Usb plugged into the first USB port).
I load Cobra USB Manager but no games are listed ALSO the screen looks funny. It looks like poor resolution and part of the page is cut off on the right edge of the screen.
I have been working on this for 2 days solid and cannot seem to work out what the problem is.
EDIT: Comparing the Cobra USB Manager screen to the picture in the Cobra User Manual it ooks like there is a strip around the whole screen missing. The resolution is so poor that when I insert external HDD into USB slot 2 down the bottom of the page I am only guessing it says USB#2. However it seems to be detecting the external HDD but not the game on it.