I've been having a bad time with my iPod Nano and Slackware Linux lately. A lot of the problems I had don't even need a description, but I give just some keywords : 'HashInfo' , 'SysInfoExtended' , 'Database Sync'.
's all,
All of  them were solved by building the last stable release of libgpod with this configuration:
./configure -prefix=/usr --libdir=/usr/lib --with-hal-callouts-dir=/usr/libexec/scripts
That's all, have fun.