This may have been caused by the revised schedule of Daylight Savings and your PC is not in synch.
1. Open Control Panel (small icons view), and click on the Date and Time option.
2. Click on the Internet tab from top.
3. Click on the Change settings button.
4. Click Yes if prompted by UAC.
5. Check the box next to Synchronize with an Internet time server.
6. Select the server from the drop down list and click Update now button.
7. Click Ok to finish.
Then log out and back into iRacing.