Client computer not updating time
Open a command prompt and type in the word date and press enter. If you get an error, however, then try running the command prompt as Administrator.If you get an error message like “A required privilege is not held by the client” when trying to use the command prompt, go to Control Panel, Administrative Tools, Local Security Policy and then navigate to Local Policy\User Rights Assignment and ensure that Change the system time and Change the time zone privileges are given to Administrators.Note that if you are in a domain, you may simply be restricted by the group policy set by your company.
You can then perform a clean boot of Windows 7 to narrow down the issue.
You can run SFC by opening a command prompt and typing in the following command: System file checker will verify all system files and will replace any file that is corrupt, modified or damaged. Just type in the word time and you can change the time too: Note that the time is in 24-hour format and you can specify it down all the way to milliseconds.
You can also change the date and time in Windows using the command line. You should be able to change the time without having to open an elevated command prompt.
Sometimes a conflict can occur and a third party program might prevent you changing the time.
Hopefully one of the solutions above fixes your issue.
I recently ran into a problem on one of my Windows 7 machines where I could not change the date and time.