Thanks for the prompt response..
I have checked & tried variations in the security options in both Firebird & IE (they were at default anyway), sadly no joy...the certificates are still being asked for.
Besides, I'm thinking that if this is happening across both browsers plus I get the EXACT same 'Client Authentication' window using either browser suggests that it's the remote site, that & the message 'the website that you want to view requests authentication' in said window (of course windows could be lying through it's teeth - wouldn't be the first time!) However I have had no other problem with any other webpages, secure or otherwise, which leads me to believe it's some sort of external problem...
Feel free to correct me if I'm wrong
Oh, just in case this helps...(long shot I know...)
Media Center Registered 10.0.27 -- D:\Program Files\J River\Media Center10\
Microsoft Windows XP Workstation 5.1 Service Pack 1 (Build 2600)
AMD Athlon 1999 MHz MMX / Memory: Total - 523 MB, Free - 130 MB
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.5) Gecko/20031007 Firebird/0.7
MS IE 6.0.2800.1106.xpsp2