Using Audio Editor 4.1.1.254, it seems that every mp3 or wma file I try loads in, then gives me a error indicating a sample format not supported by audio card. The files play fine using windows media player etc. The files are loading as 44100 Hz, 16-bit, 2 channels. i tried some other settings, but nothing seems to work.

I've got to be missing something obvious.

Figured it out! It turns out when I installed Skype, it had changed my Audio sound playback to Modem 0 sound playback instead of my SB x-Fi Audio.

Control Panel - Sounds and Audio Devices - Audio Tab - Sound playback

Once I changed that looks like everythings working!!