I have an application that is using ASP.NET 4.0 Webforms on IIS 6.0 that has been operational for multiple years. A recent deployment to the app has caused some very random (to us) intermittent issues in the Safari browser (not any other browser).
After a server reboot the application seems to work fine for periods of time, but then it will 'break'.
It is 100% server level, as it works find on all computers until it 'breaks'. Once broken, it is broken across every computer running that exact version of Safari. It you change the Safari version, or switch between http and https it will work again, until that version 'breaks'
It seems that the breaking is linked to the headers sent to the server.