I messed around with some bookmarks tonight, and the same thing is happening with the bookmarks. To reiterate, say I create a bookmark at the 35:00 mark. Shut down the unit. Wait a couple seconds like a good boy, then turn it back on. Resume the recent bookmark, and the time on the WPS shows 35:00, but the audio is something that I heard around the 30:00 mark - I haven't really pinpointed exactly how much time it's off by. Also, I noticed that if I fast forward slightly - say to the 35:10 point, the audio _seems_ to be correct IE: it's audio that's really at the 35:10 point, and not 30:10.
Soap, I'd love to be able to pinpoint it, but I kinda 'took some time off' from updating the Rockbox builds... There's probably a gap from Sept - Oct til about the middle of January when I didn't do any updating. Since January, I've been updating it about once a week, hoping that it's fixed again.
I did not try to resume smaller files - for example, a normal song. I will try that tomorrow.