This usually results in a permissions error. It's unable to read session data, so it's not able to read or write to the appropriate files. Ensure your read and write permissions are set up correctly. If this continues, it would appear to be an issue with IIS. a fresh install would resolve.
Go to windows/temp, right click then properties. After that, click security tab and click edit, then add. Write IIS_IUSRS in the box and save. Then give that user full control and save.