Yesterday, I thought I resolved the issue of "Unable to validate data" by changing the Web.config file to turn off the enableViewStateMac setting. But, today, I got a situation where the following error was returned:

"Unable to read beyond the end of the stream"

I am pretty sure this is related. Because, I never received that error before. This is the stack trace:

at System.IO.__Error.EndOfFile()
   at System.IO.BinaryReader.ReadString()
   at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
   at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
   at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
   at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
   at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
   at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
   at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
   at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
   at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
   at System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader)
   at System.Web.UI.ObjectStateFormatter.Deserialize(Stream inputStream)

So, what is triggering that anyway?