Does the speed start off fine and then gradually slow down? Or does it start fine and then there's a specific point in time at which it jumps to slow? Or is it slow the entire time on the PC? If the last, sounds like a sample rate mismatch between the WAV header and the data. You should be able to use a WAV editor to change the WAV header's sample rate to match the data. Note: this is -not- resampling, and should take place nearly instantaneously. If it takes time, then you're resampling, and that's not what you want to do.
If the either of the former...dunno what to say.