Ipod 4G after compact flash upgrade, USB connection not working correctly

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Hello
I have an iPod 4G Clickwheel. I installed a SD to Compact Flash Adaptor, plugged into a Compact Flash to 50 pin adaptor into my iPod.
I was able to perform a restore in Itunes and then reinstall Rockbox.
I use MediaMonkey for transfers. When using the original firmware, I can connect the iPOd to my PC via USB and successfully perform file transfers.
Those files are visible in Rockbox and I was able to build the database and access files.

When I'm in Rockbox and connect the USB cable, Rockbox freezes. After a few seconds it diplays USB Keypad Mode. I have it set to Multimedia. After it displays the icon, it becomes unresponsive again. Previously, I was able to use the multimedia keypad funtion immediately. A few seconds after unplugging the cable I get the following error message:
*PANIC*
mount: 0
pc: 0004F450 sp: 000C04
bt end

If I turn off HID mode: I connect the USB, after a few seconds I see the USB plug icon, but the iPod never connects as a drive. When I unplug, I get the same error as above.
So I'm forced to go to the original firmware for file transfers, which isn't the end of the world. I like having the extra space in the iPOd.

Any ideas? Might there be some drive features that this compact flash adapter is missing? Some settings I can tweak?
Thank you