Build: 10.50.4270, KB: 2777358
Many fixes are rolled up in this KB, some of the interesting ones for me (Since I primary focus on the engine) are..
KB2708012, EventID 833 logged in error log when VSS snapshot backup is taking place and write operating occurs.
This is interesting, because Error 833 is ..
SQL Server has encountered <n> occurrence(s) of I/O requests taking longer than 15 seconds to complete on file [<full path of file>] in database [<database name.>] (<dbid>). The OS file handle is <file handle>. The offset of the latest long I/O is: <offset in hexadecimal>
This is usually you have disk I/O issues, but in this case nope. It is a “internal members of the overlapped structure is not initialized correctly”.
KB2770258, You receive in incorrect result when you run a query against a partitioned table in SQL Server 2008 R2.
There are other issues that have been fixes in this CU, might be worth a quick gander to see if any of these apply to you.