Cause: Somebody has changed the computer date/time or time zone.


Solution: Double-click on the clock on the Windows task bar and correct the time. 


It may also be a good idea to have your computer synchronise with an Internet clock, such as time.windows .com. This means your computer time will always be accurate.


To synchronize you computer with an Internet time server:


Using Windows Explorer, go to Control Panel -> Clock and Region -> Date and Time - > Set time and date -> Internet Time -Change Settings as show below.


 Next select the time server you wish to synchonize with and 

select UpDate Now and finally press OK.