This probably sounds dumb, but...
...if software can take over a machine like this and lock it out, then Windows is so badly designed/flawed it should be pulled from market until it's fixed. I'm not talking about some badly behaving app, but a piece of malware that can be this incredibly destructive (from a user perspective)? Think about it, if the lock on your front door could be so easily circumvented you'd send it back for a refund or the manufacturer would do a recall.
BTW what versions of Windows are affected? Is Vista vulnerable to this? What exploits does it use? Are machines that are patched and up-to-date still affected?