I’ve seen this error around a few times over the last while but have never really paid too much attention to it:

It seems it only occurs in the management console if you have IE9 installed on your Exchange 2010 SP1 server. Previously the recommendation was to uninstall IE9 or just live with it. I recently installed Update Rollup 5 for Exchange 2010 SP1 in my lab environment and it seems to have fixed this error.

Obviously I would recommend thorough testing before deploying any updates in production, but I thought it would be worth mentioning that it does seem to fix this error as well.