"Failed to launch a critical file. Please close all other applications (note: this doesn't work), temporarily deactivate your antivirus software (note: nope, this doesn't either), and try again. Alternatively, log in as an administrator (note: which I am, and also run as an administrator too) and try again."
Seriously guys, first SCII gets botched w/patch 1.5, and now you've broken D3? When's WoW gonna go down?