Mine did the exact same thing on Apr 2. I saw the update popup in my taskbar and I just clicked on it to get it started. It said to leave the laptop plugged in on AC power and to make sure that it stayed plugged in. I let it do its thing and came back to it later. The screen was displaying an error message and everything was locked up. No mouse movement, no nothing. I called Toshiba immediately and spoke with their tech support. After explaining everything they said that I would have to send it to them to have it repaired. It would take 7 - 10 business days, plus however long it took to deliver to the depot and send back. So currently, because of THEIR update, I am f'ed from my files and getting work done.
I am getting the prepaid shipping box from Toshiba today to put in the mail tomorrow. As soon as I get something back or an update, i will post.