Windows XP CalDAV sync error

I have Em Client installed on my Windows 7-based PC connecting to a SOGo CalDAV server and it syncs up and down perfectly. However, when I try to run this same setup on my Windows XP-based systems, I get a sync error that says the connection to my calendars has failed. I am using SSL, and have installed the certificate but it still halts on this error. Windows 7 doesn’t exhibit the same behavior. Any suggestions?

My Windows XP systems are SP2 with .Net 2.0.

we fixed some issues that caused errors with this server. I tested it on XP and it worked fine. Can you please paste here complete text of the error you get?