IIS authentication - help please!!

I've just moved from win98/PWS to XPPro/IIS.

Having set the IIS directory to the local version of my new site it works in IE but when I try to view it in Opera I get:

"The server requested a login authentication method that is not supported."

There's an explanation (of sorts) as to why on the Opera site support pages but not much in the way of ways to cure it. Similarly the IIS help isn't much help; I've tried changing various settings which it suggests, to no avail (except sometimes I get a 403 forbidden message instead!).

There must be a fix; I can't be the only person to ever have run up against this while testing a new site in Opera on XP.

Help! Anyone?!

Ta

IF this is for development purposes, you can fix it in IIS permissions by right clicking on the web and choosing "Directory Security".. adjust the anonymous login to use the login credentials of your windows logged on user....

hopefully that sets you on the path, i'd post more info if i had time, but i dont right now

Thanks MorningZ, I'll give that a go. I have been into that area before, maybe I've just not selected the right options yet.