The only other times I've heard of the resest button not working, the user just wasn't hitting it right...its kinda easy to pseudo-click it.
The rockbox devs have been playing around a fair bit with playback in readiness for 3.0, which had resulted in some sketchiness...but I thought those issues had been largely resolved.
If you are using an up to date build you may like to report this over at the rockbox forum...