can't change security settings

hi i am using wndows xp and when i go to certain pages it prompts for certificates or says security settings do you want to continue internet options custom level says medium change it reset get out go back and its back to medium what am i doing wrong

 

the rest of the story

tried that no help. the rest of the story is i have 2 cpus 1 for home 1 for work a laptop both with xp. go to my work related website at home fine no problem right in try at work flashes prompt for certificate cannot get it to go away. hit yes to proceed and it goes on in and i can work but it is annoying when i can't get it to stop when it doesn't do it at home. i thought security settings might stop it but both cpus are at medium and will not change

 

You may want to try this. Go to windows update, and do the Custom Update, and see if the Root Certificates Update is available to you.

 

figured it out

i use a vehicle diagnostic software that expires monthly and since my dealership only gets 1 copy i use the expired and the other techs use the new disc. to accomplish this i set my cpu date back 1 month. the website i use as my home page issued a new certificate and explorer said it was out of date or invalid. reset the clock worked fine so when i get the next disc my cpu date will catch up with he certificate thanks for the help.