Thanks for all the replies.
Andrew: I checked and I have wmp on my PC. I can play the WMA files natively using WMP. So thats strange.
Something's disconnected somewhere.
I just tried RealBand (no I hadn't thought of doing that) and it's giving the same error. So that tells me its core to both applications so most likely system related.
I'm a developer so I'm trying a clean install again just to see if that makes any difference... lol. You might have to be a developer to get that joke.