Excellent! Congratulations and nice work. I was just coming in to check on things and start looking for solutions. Please mark this thread as [SOLVED] using the option in 'Thread tools' on the upper right.
I think you'll find Rockbox enhances your Nano quite a bit. I'll give you some unsolicited ideas here. To play all your music (lets assume all your music is in a folder called 'Music'), click and hold down the select button while the Music folder is highlighted and choose one of the 'enter folder as playlist' options. This will queue up all the songs in your Music folder. This may sound obvious, but it took me awhile to figure out I use this as a replacement for Apples 'play all' and prefer this method over messing with the Database feature.
The other thing is you can now play movies/film on your nano. The trick is the video needs to be an mpeg, and it needs to be converted to a very specific size to play. I have worked out a way to convert video to work specifically for the Nano. First, you must install mencoder, if you haven't already. You may also need ffmpeg. I cannot remember, but if you have installed all the codecs for internet and movie viewing, you likely already have it.
Then, run this command and replace "/path/to/your/old_video.extention" and "/path/to/your/new_video.mpeg" with the appropriate paths.
sudo apt-get install mencoder
Note this command is for converting different file types (ie: .avi files) into mpegs as well as reformatting existing mpegs for playing on your Nano. If you find the quality of the new video is too small, replace the value after "vbitrate=100" to a higher number than 100. Just remember the higher that number, the larger the final filesize will be.
mencoder "/path/to/your/old_video.extension/" -o "/path/to/your/new_video.mpeg" -of mpeg -oac lavc -lavcopts acodec=mp2:abitrate=192 -af resample=44100:0:0 -ovc lavc -lavcopts vcodec=mpeg2video:vbitrate=100 -vf scale,harddup -ofps 25 -zoom -xy 176
Lastly, you can now help improve your battery life by dimming the backlight. Adjust through "Settings> GeneralSettings> Display> LCDSettings> Brightness". I usually keep mine between 4 and 6. Why Apple didn't include this kind of functionality is beyond me. I suspect it was to drive people to their more expensive models.
Okay, enough unsolicited blathering. I'm just trying to make up for the fact that I didn't know how to fix your original problem Really though, if you have any more questions about Rockbox on the Nano, don't hesitate to private message me. I've been working with Rockbox on Nano for about 2 years now and, although the initial transition can take getting used to, the payoffs are huge.
And again, nice work. You're obviously a very self-reliant person