Can activate features fine on a site collection.  Can add task web part to a page fine.  However, I can't access the K2 administration tab in central admin.  Get the following error (I disabled friendly errors):

The resource object with key 'labelCentralAdmin' was not found.   at System.Web.Compilation.ResourceExpressionBuilder.ParseExpression(String expression, Type propertyType, ExpressionBuilderContext context)
   at System.Web.UI.BoundPropertyEntry.ParseExpression(ExpressionBuilderContext context)
   at System.Web.UI.ControlBuilder.FillUpBoundPropertyEntry(BoundPropertyEntry entry, String name)
   at System.Web.UI.ControlBuilder.AddBoundProperty(String filter, String name, String expressionPrefix, String expression, ExpressionBuilder expressionBuilder, Object parsedExpressionData, Boolean generated, String fieldName, String formatString, Boolean twoWayBound)
   at System.Web.UI.ControlBuilder.PreprocessAttribute(String filter, String attribname, String attribvalue, Boolean mainDirectiveMode)
   at System.Web.UI.ControlBuilder.PreprocessAttributes(ParsedAttributeCollection attribs)
   at System.Web.UI.ControlBuilder.Init(TemplateParser parser, ControlBuilder parentBuilder, Type type, String tagName, String id, IDictionary attribs)
   at System.Web.UI.ControlBuilder.CreateChildBuilder(String filter, String tagName, IDictionary attribs, TemplateParser parser, ControlBuilder parentBuilder, String id, Int32 line, VirtualPath virtualPath, Type& childType, Boolean defaultProperty)
   at System.Web.UI.TemplateParser.ProcessBeginTag(Match match, String inputText)
   at System.Web.UI.TemplateParser.ParseStringInternal(String text, Encoding fileEncoding)

I would recommend opening a formal support ticket on this issue.

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I just hit the same error.  I believe it is a bug caused by central admin not being installed on the default drive.  In my case, central admin was in D:\inetpub\wwwroot\wss.  It seems that AdminResource.resx was never deployed to the App_GlobalResources folder.  I copied it over there and it started working properly.