mscorlib error when updating

[Xilrath]

I keep getting this error when trying to update:

Error Getting File List: mscorlib
at System.Security.Principal.SecurityIdentifier..ctor(WellKnownSidType sidType, SecurityIdentifier domainSid)
at System.Diagnostics.SharedUtils.EnterMutexWithoutGlobal(String mutexName, Mutex& mutex)
at System.Diagnostics.SharedPerformanceCounter.GetCounter(String counterName, String instanceName, Boolean enableReuse, PerformanceCounterInstanceLifetime lifetime)
at System.Diagnostics.SharedPerformanceCounter..ctor(String catName, String counterName, String instanceName, PerformanceCounterInstanceLifetime lifetime)
at System.Diagnostics.PerformanceCounter.Initialize()
at System.Diagnostics.PerformanceCounter.set_RawValue(Int64 value)
at System.Net.NetworkingPerfCounters.Initialize()
at System.Net.Configuration.SettingsSectionInternal..ctor(SettingsSection section)
at System.Net.Configuration.SettingsSectionInternal.get_Section()
at System.Net.HttpWebRequest.get_DefaultMaximumResponseHeadersLength()
at System.Net.HttpWebRequest..ctor(Uri uri, ServicePoint servicePoint)
at System.Net.HttpRequestCreator.Create(Uri Uri)
at System.Net.WebRequest.Create(Uri requestUri, Boolean useUriBase)
at System.Net.WebRequest.Create(Uri requestUri)
at System.Xml.XmlDownloadManager.GetNonFileStream(Uri uri, ICredentials credentials)
at System.Xml.XmlDownloadManager.GetStream(Uri uri, ICredentials credentials)
at System.Xml.XmlUrlResolver.GetEntity(Uri absoluteUri, String role, Type ofObjectToReturn)
at System.Xml.XmlTextReaderImpl.OpenUrlDelegate(Object xmlResolver)
at System.Threading.CompressedStack.runTryCode(Object userData)
at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup( TryCode code, CleanupCode backoutCode, Object userData)
at System.Threading.CompressedStack.Run(CompressedStack compressedStack, ContextCallback callback, Object state)
at System.Xml.XmlTextReaderImpl.OpenUrl()
at System.Xml.XmlTextReaderImpl.Read()
at System.Xml.XmlTextReader.Read()
at System.Xml.XmlReader.MoveToContent()
at System.Data.DataSet.ReadXml(XmlReader reader, Boolean denyResolving)
at System.Data.DataSet.ReadXml(String fileName)
at WindowsApplication7.Form1.DownloadExtras()This operation is only supported on Windows 2000 SP3 or later operating systems.

Could this be due to changing over to the x64 version of windows? Any help would be appreciated.

EDIT: All drivers, etc. are 64 bit versions, and I am running the .NET 2.0 beta.