Outlook 98 Time Corrupt?

Monthly I send an e-mail to remind certain people that on a particular Friday of the month they are supposed to remember to do a specific thing. I set the options to not deliver the e-mail before Thursday at 12:00 p.m., yet it delivers it on Wednesday or Tuesday at a random time. I have had the servers checked for possible time error, my PC clock is current as is Outlook time. Any ideas why this happens and how I can get it to act correctly again?