SSL and PHP = problems?

I have a webpage that uses php4 and a SSL connection for some sensitive information like credit card number and such, it's a registration process. When MacOS users access the page it all goes well and no problems at all. But... when PC/Windows users access the page they get some problems and it shows every now and then so it's hard to know what causes it. I have a screenshot of the error that accure that causes them to do the registrationprocess again and it's a bit annoying: http://www.programmering.nu/felmeddelande.gif Do you think this is because of bad PHP-programming or is it because of the SSL, or do you have any other sugestions? I find it hard to beleve that it is because of the programming because before the SSL-connection when I only have a regular HTTP-connection there were never any problems, and it works fine with MacOS users. Please help! ;) Thanks. /Magnus Hammar --------------