Need help with a security issue with XP and the internet.

[DGath]

I posted this same question in the Internet forum not too long ago, but after trying to solve it I have realized some more things and the problem pertains more to XP than the internet so here goes...

I get usually at least four or five windows login prompts every time to I goto a website that has ads on it. Here's a few screenshots...
http://people.ku.edu/~dgath/login1.jpg
http://people.ku.edu/~dgath/login2.jpg

This is really really annoying. I am using XP pro and recently changed some security setting in order to run IIS 5.1 securely on my computer. With each one of these login prompts, it is asking me to login into say... serveby.adimages.com. I have now figured out that if I use one of the local user accounts on this computer as the login information, the prompt goes away.

So for example, a user's name on my computer is Bob and his password is Computer, when the webpage loads up and it prompts me to log in to global.msads.com, if I type in Bob and the password Computer, that prompt goes away and I'd assume it means that I successfully logged in.

While I am certain I am not logging in to these actual servers, there must be some security setting on my computer that is requiring authentication in order to go that route. I don't know, I'm not the brightest person in the world when it comes to security and networks, I know the basics, enough to run IIS, so I don't understand why this is happening. It makes surfing the internet suck ass. And by the way, this is true for all browsers that I use, not just IE, so it's not an internet thing, it's a security thing on XP that just happens to arise when the internet is active.

Any ideas? Sorry for the posting in different forums, but unlike I origionally though, it's an XP problem, so I wanted to see if the XP people had any ideas.

Maybe a good starting point would be if someone could tell me what's so unique about these adservers compared to normal webservers because I'm only being asked to log into the web servers.

[DGath]

Ok, well I finally figured it out... I think. Rather than just delete the post, I figure I'll leave it up in case anyone else has this problem in the future.

The solution? In Internet Explorer goto Tools > Internet Options > Security > change the custom level for the internet. Now scroll to the bottom and where it says user authentication, change the user logon to "Anonymous logon" and it should be fixed. Anyone see any security problem with this setting? I don't know if this is the default setting or if I screwed something up before and this is just a way around my problem.

So thank god, back to normal surfing. If you want to see how much it sucked, change that setting and you will want to kill yourself.

[The Tool]

Default is "Automatic logon online in Intranet zone".

[dElite]

I am having the exact same problem but it affects both IE and FF. I am led to believe that this is in someway related to a ad bot/Spyware that's on my system. I've ran AA, SB S&D, MS Anti-Spyware, Clamwin, F-Secure, and SymantecAV. All found bits and pieces of this thing and clean it off, except for this annoying side effect. My guess is that it's intention is to replace ads in pages with their own in order to execute click fraud. Did you experience a similar effect in FireFox?