Right click the clock, then select 'Adjust Date/Time', then go to the Time Zone tab and check that it's set to GMT (Dublin, Edinburgh, Lisbon, London), and that the box is ticked to automatically adjust for daylight saving. Then go to the Internet Time tab, and check that the box is ticked to automatically synchronise with an Internet time server. Mine is set to time.windows.com. Come back to us if that doesn't cure things.