Can you install Microsoft Silverlight from microsoft.com and are you able to open the Preferences without it crashing?
I'm trying to isolate this problem, and it could be a Mac problem, or a Silverlight problem.
I am hearing that it works fine on some people's Macs and not on others, but there is no obvious pattern to it. It could be that it doesn't work on particular versions of Mac OS X, or it could be that 3rd party software that some people use, messes up Silverlight.
Unfortunately, I don't have a Mac lab to try it out on several computers so I would really appreciate some feedback on this if you have a Mac.
If you have a PowerPC based chipset or a Mac with a version older than 10.6 (Snow Leopard) then you probably should not bother testing this because Silverlight only supports Intel chipsets and 10.6 and up.
If you are able to test out the latest version of Silverlight 5, please list your exact Mac OS X version, and what version of Silverlight installed fine for you.
If you run into a problem, please list the problem.
Thank you very much for your help!
(If you are interested, I have a recent question on StackOverflow that goes into more technical detail about this.)