php date bug ?

hi, i've got a calendar and i produce a month sort of outlook / filofax view that shows the user's appointments for that month. the way i was building it was but defining ADAY in the following manner: define("ADAY", (60*60*24) ); once i'd done evrything i needed to do i incremented the timestamp for the day by ADAY. all seemed ok but then one of the users pointed out that October 28th appeared twice and then month had 32 days in for this year. after a bit of head scratching we realised that the clocks go forward (any foreign readers please excuse the rediculous way the british time system works) and technicallay i guess october 24th has 25 hours. thus the time was incremented to a stamp within the same day. redfining the stamp as $start3=mktime(0,0,0,$dayArray[mon],$dayArray[mday]+1,$dayArray[year]); does work however ? is it php or the server that's at fault ? Steve