WMP11 bitrate conversion -> file corruption?

I'm using WMP11 on (XP SP2) to sync my Sandisk Sansa M240. I've used the
advanced sync options to specify that all content copied to the device should
be at 128Kbps, so most of my music gets converted. Frequently, however, an
album will get corrupted on the player such that all of the songs have 0:00
length. If I try to play one of them, the player pauses. If I back out of
that album, every track on the player inherits the info of the corrupted
track- it's as if I'd copied the same file a thousand times. Anyone else
seen this? Any fix available? I have the latest Sansa firmware and I've
reformatted the device a couple of times, but that hasn't helped.