There has been an issue discovered if you have Windows 2008 R2 and SharePoint 2010, and you install any of the following fixes KB2769369, KB2757638, KB2756920, KB2742598, KB2742598, or KB2736418. You may notice the following symptoms
While the SharePoint site framework loads; no authenticated content will load or is accessible. SharePoint becomes entirely useless to users and admins. This does not happen immediately after patching; It seems to take several hours after the reboot for the current token to expire.
As well you will notice errors in Event logs or ULS logs that are excessively chatty and bloated with this failure… but the common trace element seems to be in: '/SecurityTokenServiceApplication/securitytoken.svc'
The following article KB2801728 was recently made available for your review.
If you have installed any of the above then please consider installing the recommended fix KB2637518 , the workaround from this fix is to insure that System.ServiceModel.dll and System.ServiceModel.WasHosting.dll are in sync.