Secure Web Sites

I have a problem with a secure web site. I can login then it takes me to another window but it will not let me in and says the site is unavailble but it isn’t. If I look in the address bar it should say https://xxx.xxxx.xxx but the s is missing if I add the s in it will let me in to the site. Somehow internet explorer is taking the s off has anyone ever ran into this before?