I got this same error tonight for the first time and have been running version 1.30 for a couple of weeks now with no problems. After reading everything here, I uninstalled the program, rebooted, then cleaned the registry with a few cleaners (Ace Utilities, CCleaner, RegVac and TuneUp Utilities 2008). Ace Utilities was the only program that found any keys and I deleted them. I then re-installed the program and it is running fine now. Must have been a fluke as the keys Ace Utilities found were the usual stuff (MUICache entries, etc.) Today I did install and had SUPERAntiSpyware running earlier today but disabled that after I has the error. Maybe both of them running at the same time can cause problems?
Silverlight is Micorsoft's answer to the flash war they are having with Adobe. Some of their sites are going that route now and need to have Silerelight installed to take full advantage of some things the have to offer.