I remember rockbox occasionally halting/stalling (always without timestretch - it was before I figured out that existed - which is long before my skin) and making that looping "trrrrrrrrrrr" sound just like in BSODs. It wasn't very frequent, but it was there. With Timestretch enabled, it never happened. It might have been fixed in the newest (2013ish) rockbox available for maemo though, no idea about that - don't plan in disabling Timestretch :P