The past couple of days I've gotten the same exception when trying to load the Client. At first I thought it was a badly uploaded/corrupted league file, but two days in a row it shouldn't happen with a fresh file on the second day.
Exception Type
----------------
System.Runtime.Serialization.SerializationException
Message - Source
-----------
End of Stream encountered before parsing was completed. - mscorlib
etc...
![Image](http://www.sichl.com/images/STHS_Client_Error.png)