Windows – WSUS clients failing to get updates with error 80072EE2

We recently implemented WSUS for our Windows workstations (about 90). Some of the clients seem to have no problem, while others keep returning the error "80072EE2" when attempting to manually check for updates using Windows Update.

Clients are Win7 x64 SP1, server is Win2008 x86 SP2

Our workstations use a standard image, so there is minimal difference between systems.

The process w3wp.exe on the server spikes to very high CPU for extended periods of time.

In the problem clients' WindowsUpdate.log, we see:

2015-12-04  11:12:33:847     968    12ac    PT    Server URL = http://server.domain.com/SimpleAuthWebService/SimpleAuth.asmx
2015-12-04  11:13:37:937     968    12ac    Misc    WARNING: Send failed with hr = 80072ee2.
2015-12-04  11:13:37:937     968    12ac    Misc    WARNING: SendRequest failed with hr = 80072ee2. Proxy List used: <(null)> Bypass List used : <(null)> Auth Schemes used : <>
2015-12-04  11:13:37:937     968    12ac    Misc    FATAL: SOAP/WinHttp - SendRequest: SendRequestUsingProxy failed. error 0x80072ee2
2015-12-04  11:13:37:937     968    12ac    PT    + Last proxy send request failed with hr = 0x80072EE2, HTTP status code = 0
2015-12-04  11:13:37:937     968    12ac    PT    + Caller provided credentials = No
2015-12-04  11:13:37:937     968    12ac    PT    + Impersonate flags = 0
2015-12-04  11:13:37:937     968    12ac    PT    + Possible authorization schemes used = 
2015-12-04  11:13:37:937     968    12ac    PT  WARNING: SyncUpdates failure, error = 0x80072EE2, soap client error = 5, soap error code = 0, HTTP status code = 200
2015-12-04  11:13:37:937     968    12ac    PT  WARNING: PTError: 0x80072ee2
2015-12-04  11:13:37:937     968    12ac    PT  WARNING: SyncUpdates_WithRecovery failed.: 0x80072ee2
2015-12-04  11:13:37:937     968    12ac    PT  WARNING: Sync of Updates: 0x80072ee2
2015-12-04  11:13:37:937     968    12ac    PT  WARNING: SyncServerUpdatesInternal failed: 0x80072ee2
2015-12-04  11:13:37:937     968    12ac    Agent     * WARNING: Failed to synchronize, error = 0x80072EE2
2015-12-04  11:13:37:937     968    12ac    Agent     * WARNING: Exit code = 0x80072EE2

Checking the WSUS server SoftwareDistribution.log, we see:

2015-12-04 16:14:36.018 UTC     Error   w3wp.18 ClientImplementation.SyncUpdat
        Syst
em.Threading.ThreadAbortException: Thread was being aborted.
   at Microsoft.UpdateServices.Internal.NativeMethods.ExtractBlobFromMemoryCab
UInt32 cbCompressed, Byte* pCompressed, UInt32& pcbUncompressed, IntPtr& ppUnc
mpressed)
   at Microsoft.UpdateServices.Internal.CabUtilities.ExpandMemoryCabToString(B
te[] src)
   at Microsoft.UpdateServices.Internal.DataAccess.ExecuteSpGetCoreUpdateXml(I
t32[] revisionIds)
   at Microsoft.UpdateServices.Internal.DataAccessCache.GetCoreUpdateXml(Int32
] revisionIds, DataAccess da, Int64 maxXmlPerRequest)
   at Microsoft.UpdateServices.Internal.ClientImplementation.GetSyncInfo(Versi
n clientProtocolVersion, DataAccess dataAccess, Hashtable stateTable, Hashtabl
 deploymentTable, Boolean haveGroupsChanged, Boolean driverSyncNeeded, Boolean
doChunking)
   at Microsoft.UpdateServices.Internal.ClientImplementation.SoftwareSync(Data
ccess dataAccess, UnencryptedCookieData cookieData, Int32[] installedNonLeafUp
ateIds, Int32[] leafUpdateIds, Boolean haveGroupsChanged, Boolean expressQuery
 Guid[] filterCategoryIds, Boolean needTwoGroupOutOfScopeUpdates)
   at Microsoft.UpdateServices.Internal.ClientImplementation.SyncUpdates(Cooki
 cookie, SyncUpdateParameters parameters)
   at Microsoft.UpdateServices.Internal.ClientImplementation.SyncUpdates(Cooki
 cookie, SyncUpdateParameters parameters)
   at Microsoft.UpdateServices.Internal.Client.SyncUpdates(Cookie cookie, Sync
pdateParameters parameters)
   at System.RuntimeMethodHandle._InvokeMethodFast(Object target, Object[] arg
ments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeTypeHan
le typeOwner)
   at System.RuntimeMethodHandle.InvokeMethodFast(Object target, Object[] argu
ents, Signature sig, MethodAttributes methodAttributes, RuntimeTypeHandle type
wner)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invo
eAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVi
ibilityChecks)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invo
eAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at System.Web.Services.Protocols.LogicalMethodInfo.Invoke(Object target, Ob
ect[] values)
   at System.Web.Services.Protocols.WebServiceHandler.Invoke()
   at System.Web.Services.Protocols.WebServiceHandler.CoreProcessRequest()
   at System.Web.Services.Protocols.SyncSessionlessHandler.ProcessRequest(Http
ontext context)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpAppli
ation.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& com
letedSynchronously)
   at System.Web.HttpApplication.PipelineStepManager.ResumeSteps(Exception err
r)
   at System.Web.HttpApplication.BeginProcessRequestNotification(HttpContext c
ntext, AsyncCallback cb)
   at System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerReque
t wr, HttpContext context)
   at System.Web.Hosting.PipelineRuntime.ProcessRequestNotificationHelper(IntP
r managedHttpContext, IntPtr nativeRequestContext, IntPtr moduleData, Int32 fl
gs)
   at System.Web.Hosting.PipelineRuntime.ProcessRequestNotification(IntPtr man
gedHttpContext, IntPtr nativeRequestContext, IntPtr moduleData, Int32 flags)
   at System.Web.Hosting.UnsafeIISMethods.MgdIndicateCompletion(IntPtr pHandle
, RequestNotificationStatus& notificationStatus)
   at System.Web.Hosting.PipelineRuntime.ProcessRequestNotificationHelper(IntP
r managedHttpContext, IntPtr nativeRequestContext, IntPtr moduleData, Int32 fl
gs)
   at System.Web.Hosting.PipelineRuntime.ProcessRequestNotification(IntPtr man
gedHttpContext, IntPtr nativeRequestContext, IntPtr moduleData, Int32 flags)
2015-12-04 16:14:36.018 UTC     Warning w3wp.18 SoapUtilities.CreateException
Throw
Exception: actor = http://server.domain.com/ClientWebService/client.asm
, ID=9b1e3f5a-f766-4ba9-bf7e-52c7cfbe1f68, ErrorCode=InternalServerError, Mess
ge=, Client=a39b9446-c45a-4060-851d-9157a2393278

What we've tried:

1. Rebooting the server
2. Changing Automatic Updates check for updates period from 1 hour to 10 hours
3. Disabling AV on-access scanning on server
4. Updating a problem client to latest WSUS client
5. Manually browsing to the URL mentioned in the client's log above. (No issues)

I'm fairly new to WSUS so I'm not really sure what else we can check. Any help would be greatly appreciated.