Synchronize to continue music subscription while shuffling.

I’ve been getting a “synchronize to continue music subscription” error occasionally on my sansa.  Most of my music comes from cd’s that i’ve ripped to windows media player, or music that’s downloaded from limewire. My “copy protect music” option isn’t checked off in Media Player. The error only occurs when i’m running a playlist that i created in WMP with shuffle on. If i play it without shuffle, or if i play non-playlist music then it doesn’t happen. 

Does anyone know a way i can fix this?