One hour adrift at this time of the year sounds like daylight saving.  Or compensation thereof.  What is your computer clock set to (not what time the clock reads)?

Personally I think it rather naughty that [at least older] Windoze automatically sets the clock one hour forward the first reboot after the spring switch forward, and the same in the autumn back.  What if you'd already done it, like all the rest of the clocks in the house?