System clock shows wrong date & time

my system runs on Win2k Professional, my system clock is showing wrong date & time. itz shows next day’s date & time. i checked with BIOS , there its seems to be ok. but only when i log into machine it shows the wrong time. besides being a restricted users am not able to change the date.

infact i did it in administrator login it works fine there. but when i login as a user i get the wrong Date & Time.

how do i fix this ??