What OS and browser are you using?
OS is Windows 10 and browser is Internet Explorer 11
Do you often change your system clock?
Never, however since my work PC is controlled by corporate policies they may get reset when I logon to the computer for the first time in the morning.
Is it set properly?
Yes
Do you have some kind of antivirus/browser cleaner software that deletes cookies and session state?
We have antivirus but this occurs on both my computer at work and at home and at home I am not currently using an antivirus. I have no browser cleaner running in the background.
Do you have JavaScript or cookies blocked?
Yes some are blocked as I have my Internet Privacy option set to Medium. This option will: Blocks cookies from a third party that do not have a compact policy. This option is set on my corporate PC by default which I can change but it will be reset back at the next login.