User's Can't access Secure sites

I and several other techs have been unable to resolve a realtively new problem. The users for no apparent reason are now unable to view secure web pages(HTTS). This is currently occuring with IE 6 and Winxp and Win98 machiines. Also the OS's are legit. Changes to the security settings(setting them as low as possible)have made no difference. Settings to the SSL versions make no difference. Installing Windows updates are not an option from the web as that will cause an error of "ActiveX" controls settings are to high. Changed those and no go. The user have talked to there ISP's as well and Owners of the secure sites. Any body have any other ideas? With out recomending a reinstall of the OS.

Thanks