iCal still shows previous day in ical proper, but shows current date in the dock

iCal is open in the MONTH, on my desktop permanently, but it continually shows yesterdays date. It isn't till I actually click on the following day in iCal proper that the date changes to the current date. The iCal icon on the dock works fine with no issues. When I first purchased the iMac iCal worked aok. Software is continually updated.