KB KB2449742 or KB2446709 may crash SQL or Exchange

http://support.microsoft.com/kb/2540222/en-us

Exchange Server, SQL Server, or PowerShell crashes after you install security update 2449742 or 2446709

Any application that has a dependency on the .NET Framework 2.0 Service Pack 2 or .NET Framework 3.5 Service Pack 1

could crash.

https://msmvps.com/blogs/wstein/archive/2011/04/18/kb-2449742-bringt-die-exchange-management-tools-zum-erliegen.aspx

https://msmvps.com/blogs/bradley/archive/2011/04/15/net-update-2449742-breaks-exchange-2010.aspx