This one is a interesting one. Again following a health check on a clients site for Lync 2010, i came across this little issue with Lync 2010 and Silverlight and thought i should blog about it as it seems the issue/resolution its not as well known as i first thought.
Symptoms of this issue is when you are administering Lync 2010 via the Lync control panel, silverlight will crash giving you a very basic crash error. (see below).
Reasons for this error, or should i say the crashing is still unknown and it logged with Microsoft. I expect Lync 2010 will be patched to resolve this.
Remove Silverlight 5.x and install Silverlight 4.x
At the time of writing Lync 2010 October CU7 has been released and the issue still exists with silverlight 5.x