Hate to look like an idiot responding to my own thread, but in the interest of sharing info here's my solution...
It was the thrice-damned Silverlight plugin. The newest one didn't work, so after painstakingly tracking down all the crap Microsoft put on my computer and nuking it, I was able to download an older version of Silverlight (4.xx), and voila! It works now.
So thank you, Microsoft, for continuing to foul up computers even when I not running Windows. Truly, thine reputation be deserved.
i have the same problem after updating Silverlight. have uninstalled & reinstalled several times. currently uninstalled newest version again, and trying to install an older version.
when installing onto my disk, it keeps telling me there is a newer version already installed, so doesn't allow me to install the older version. so i'm obviously having some trouble finding all the files to un-install.
hope they find a fix for this. i've seen this in a few other Mac troubleshooting discussion sites.
Did you get the files Silverlight has installed in your hidden directories? If you use the "Go to Folder" command under Finder, you should be able to navigate to /private/var/db/receipts. There you'll find two files Microsoft installed for Silverlight. I can't recall the names of them at the moment, but you'll know them when you see them. Delete those, and you *should* be good to go (provided you got all the easier to find ones, that is).
My coworker found this fix. The current version of silverlight won't start if the machine is running with the discrete NVIDIA GPU. Some apps need it and using an external monitor will cause it to use the discrete. Turn off all your apps and unplug the external montitor. This should put you back in the integrated Intel GPU. Now try to start a Netflix video, once its running you should be able to plug your external monitor back in and start other apps.
You can also use this utility http://gfx.io to see which GPU is being used.