extended delay on windows boot

i installed windows 7 on my 24" imac with no problems. ive had it on for over a month with no problems. i tried to start windows up yesterday and it stayed on the white screen for over 30 seconds before starting. even starting the windows installation from the cd took the same time to begin. it continues to do this over and over. i have just uninstalled and reinstalled windows 7 and it still takes the same ammount of time to start windows. osx still boots up completly fine. i tried resetting the pram and still no luck 8( im not sure where to go from here. its something i can live with if i have to but i see no reason why windows would "randomly" take this long to boot. no new programs were installed and no changes were made when the problem started