ViewState issue
<p>We are using our website on Windows server 2003 with IIS 6 and also have a test server 2003 with IIS 5.
When I tested the page with ViewState on test server, it worked fine. But we tested on other server which is running IIS 6.It gave error. I compared web configuratioin file, it looked the same. There was the machine key and maximum length for view state. I've been spending couple days and still don't find it. Somebody can help me.</p>

<p>This error doesn't happen all the time. So I think the source code is not the problem.
Here is my error</p>

<pre><code>[SerializationException: Member '_name' was not found.]
   System.Runtime.Serialization.SerializationInfo.GetElement(String name, Type&amp; foundType) +7608149
   System.Runtime.Serialization.SerializationInfo.GetString(String name) +24
   SD.LLBLGen.Pro.ORMSupportClasses.EntityBase2..ctor(SerializationInfo info, StreamingContext context) +69
   PV.Data.Standard.EntityClasses.ClinicEntity..ctor(SerializationInfo info, StreamingContext context) +26

[TargetInvocationException: Exception has been thrown by the target of an invocation.]
   System.RuntimeMethodHandle._SerializationInvoke(Object target, SignatureStruct&amp; declaringTypeSig, SerializationInfo info, StreamingContext context) +0
   System.Reflection.RuntimeConstructorInfo.SerializationInvoke(Object target, SerializationInfo info, StreamingContext context) +108
   System.Runtime.Serialization.ObjectManager.CompleteISerializableObject(Object obj, SerializationInfo info, StreamingContext context) +273
   System.Runtime.Serialization.ObjectManager.FixupSpecialObject(ObjectHolder holder) +49
   System.Runtime.Serialization.ObjectManager.DoFixups() +223
   System.Runtime.Serialization.Formatters.Binary.ObjectReader.Deserialize(HeaderHandler handler, __BinaryParser serParser, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage) +188
   System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream, HeaderHandler handler, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage) +203
   System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream) +12
   System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader) +968
   System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader) +291
   System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader) +392
   System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader) +404
   System.Web.UI.ObjectStateFormatter.DeserializeValue(SerializerBinaryReader reader) +392
   System.Web.UI.ObjectStateFormatter.Deserialize(Stream inputStream) +135

[ArgumentException: The serialized data is invalid.]
   System.Web.UI.ObjectStateFormatter.Deserialize(Stream inputStream) +199
   System.Web.UI.ObjectStateFormatter.Deserialize(String inputString) +297
   System.Web.UI.ObjectStateFormatter.System.Web.UI.IStateFormatter.Deserialize(String serializedState) +4
   System.Web.UI.Util.DeserializeWithAssert(IStateFormatter formatter, String serializedState) +37
   System.Web.UI.HiddenFieldPageStatePersister.Load() +113

[ViewStateException: Invalid viewstate. 
    Client IP: 10.0.51.92
    Port: 51267
    User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; BRI/1)
    ViewState: /wEPDwUJODUyMDU5NzIxDxYOHgpQcmFjdGljZVBrKClYU3lzdGVtLkd1aWQsIG1zY29ybGliLCBWZXJzaW9uPTIuMC4wLjAsIEN1bHR1cmU9bmV1dHJhbCwgUHVibGljS2V5VG9rZW49Yjc3YTVjNTYxOTM0ZTA4OSRlMzE4OTAzNy0xOWY3LWRmMTEtOGQwNC0wMDFlMGI2ZTE4MWEeCENsaW5pY1BrKCsEJGQyYzg3OWI4LTE5ZjctZGYxMS04ZDA0LTAwMWUwYjZlMTgxYR4IUHJhY3RpY2UFBFBDTFAeBkNsaW5pYwUKVy4gUk9CSU5TTx4M..]

[HttpException (0x80004005): The state information is invalid for this page and might be corrupted.]
   System.Web.UI.ViewStateException.ThrowError(Exception inner, String persistedState, String errorPageMessage, Boolean macValidationError) +106
   System.Web.UI.ViewStateException.ThrowViewStateError(Exception inner, String persistedState) +14
   System.Web.UI.HiddenFieldPageStatePersister.Load() +217
   System.Web.UI.Page.LoadPageStateFromPersistenceMedium() +105
   System.Web.UI.Page.LoadAllState() +43
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +6785
   System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +242
   System.Web.UI.Page.ProcessRequest() +80
   System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) +21
   System.Web.UI.Page.ProcessRequest(HttpContext context) +49
   ASP.clinicinfo_aspx.ProcessRequest(HttpContext context) in c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\9ca5f508\2be4cd8e\App_Web_sqt6xlmv.2.cs:0
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +181
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean&amp; completedSynchronously) +75
</code></pre>
