Is there any way for me to check this? I'm very sorry but I'm at a loss here as to what step to take next.

I have verified that the DNN folder has full system permissions. It doesn't seem to make sense. I can't seem to decifer the errorLogs and wish I knew the reason or how to resolve the error in the URL: /Default.aspx?tabid=39&error=String+was+not+recognized+as+a+valid+DateTime.&content=0. Thank you again for all your help. It's truly appreciated

We are getting a similar error message with DNN 5.2.2 on a W2008 R2 

The error  happens for certain users whenever they select a photo image from a list which directs the user to a new page with an image viewer.   The page behaviour is successful and correct for UnAuthenticated users.  However, all authenticated users completing the identical activity trigger this error: 

InnerException: String was not recognized as a valid DateTime.
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: System.DateTimeParse.Parse
StackTrace:
 

The permissions on the folder/file system are unchanged for two years.  SQL and Webserver are on the same box and the time is sync'd with RW.

Any suggestions are appreciated.