I found the error cause. For some reason the machine couldn't find the soundcard. Rebooting fixed the problem. As to why the soundcard would affect a wav conversion process, I don't know. Rashid.
I'm having the same problem. I can't convert even after the files have been transferred to mylibrary. Running the wav conversion tool as a standalone makes no difference. Marc's himrenderer comes up with an error too... Ideas? Thanks Rashid.