i'm having this same issue except the .xml page is reachable. When I start up WAU it shows no addons in the list although it says it is up to date. I have a feeling this is a vista issue since vista breaks everything. WAU is running with admin privledges and admins have full access to the wow folder (it's not installed in the program files directory). anyone have some suggestions?
I have no error message whatsoever, I just have wau not bringing anything up. It's winxp pro, fresh format. It's been running slower and slower each day, going from taking a few moments to update my ~160 addons to taking upwards of a minute to update the ~10 or so that actually get updates, and now it just shows a blank page.