Success at last!
I can confirm that the A Data 32GB CF Card works fine.
Direct Link:
Newegg.com - A-DATA 32GB Compact Flash (CF) Flash Card Model SPEEDY CF 32G - Retail
No alterations to the bootloader. Just did a quick format under windows, loaded the latest Rockbox files and all is golden.
Two observations:
1. Booting into stock iriver firmware gives the "check hdd connection" error but the player does eventually get there, however, you cannot access any files or navigate the player once there.
2. With the player on, plugging into a USB cable gives you the USB icon on screen but the computer does not see the player. Removing the cable does nothing and the player must be shut off. So the only way to get into USB mode is to start with the player off, plug in the USB cable and turn the player on.
Transfer speeds are a bit slow. It took approx. 15min to transfer 6GB of music onto the card. Other than that and the above mentioned items, it is sweet to have 30GB of flash based music in my iHP-120! ;D
ps - i'm thinking that the Transcend and other cards that give an error are giving it due to the sleep command. If someone could compile the bootloader altering that command, i'd test it.