system.core version=2.0.5.0 assembly not found

Ok, so it's the dreaded:
Could not load file or assembly 'System.Core, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e' or one of its dependencies. The system cannot find the file specified.
First it was just in the VS 2008 web server, and only about 90% of the time. 10% I'd get lucky and it wouldn't show up and I could debug.
The rest of the time I published to my a local directory hooked to my IIS server on my workstation (W2K8R2x64)
Now it's showing up in the published site as well.
Seems to have all started around the time I added an aspxupload control…but may have happened sooner.
Now nothing I can do will get rid of it, and it's DevExpress.Web.ASPxClasses.Internal.ResourceManager that's blowing the gasket.
I've tried fiddling with binding redirection, but either that doesn't help, or I'm doing it wrong.
It happens all over the site on any page. Below is stack trace.
Any ideas?
[FileNotFoundException: Could not load file or assembly 'System.Core, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e' or one of its dependencies. The system cannot find the file specified.]
   System.ModuleHandle.ResolveType(Int32 typeToken, RuntimeTypeHandle* typeInstArgs, Int32 typeInstCount, RuntimeTypeHandle* methodInstArgs, Int32 methodInstCount) +0
   System.ModuleHandle.ResolveTypeHandle(Int32 typeToken, RuntimeTypeHandle[] typeInstantiationContext, RuntimeTypeHandle[] methodInstantiationContext) +147
   System.Reflection.Module.ResolveType(Int32 metadataToken, Type[] genericTypeArguments, Type[] genericMethodArguments) +203
   System.Reflection.CustomAttribute.FilterCustomAttributeRecord(CustomAttributeRecord caRecord, MetadataImport scope, Assembly& lastAptcaOkAssembly, Module decoratedModule, MetadataToken decoratedToken, RuntimeType attributeFilterType, Boolean mustBeInheritable, Object[] attributes, IList derivedAttributes, RuntimeType& attributeType, RuntimeMethodHandle& ctor, Boolean& ctorHasParameters, Boolean& isVarArg) +133
   System.Reflection.CustomAttribute.GetCustomAttributes(Module decoratedModule, Int32 decoratedMetadataToken, Int32 pcaCount, RuntimeType attributeFilterType, Boolean mustBeInheritable, IList derivedAttributes) +431
   System.Reflection.CustomAttribute.GetCustomAttributes(Assembly assembly, RuntimeType caType) +88
   System.Reflection.Assembly.GetCustomAttributes(Type attributeType, Boolean inherit) +53
   DevExpress.Web.ASPxClasses.Internal.ResourceManager.FindAllWebResources(Assembly assembly) +74
   DevExpress.Web.ASPxClasses.Internal.ResourceManager.FindAllWebResources() +158
   DevExpress.Web.ASPxClasses.Internal.ResourceManager…cctor() +877
[TypeInitializationException: The type initializer for 'DevExpress.Web.ASPxClasses.Internal.ResourceManager' threw an exception.]
   DevExpress.Web.ASPxClasses.Internal.ResourceManager.ProcessRequest() +0
   DevExpress.Web.ASPxClasses.ASPxHttpHandlerModule.BeginRequestHandler(Object sender, EventArgs e) +11
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +68
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75