IUSR Account Lost Permissions, Site Unreachabl

I run IIS6 with Plesk 7.5. I was noodling around in Plesk, I believe in the 'Setup' for one of the sites turning on Custom Errors.. and then experience this problem all of a sudden:

The one site (out of 50 on the box) I was dealing with has apparently lost its IUSR password synch: if you try and access the site now, you are given a user name and password NTFS prompt.

Now.. i have done my reading on this today, and nearly six hours of sweating and cursing (its a busy ecommerce site), still NOTHING.

I realize the IUSR password is stored in the IIS Metabase, in the IIS Properties, and one other place. I tried every possible solution i could find on the subject, from copying the password out of the metabase and pasting it into the IUSR_<username> in the IIS Properties, deleting and recreating the IUSR account, and NOTHING.

Looking at all the permissions, everything is exactly as it should be. It is driving me nuts, and soon will be making me poor.. please someone give me the lightening bolt of wisdom.

This happened once before on a smaller site, and i just deleted the site in Plesk, then in IIS, and remade it and no more problems. This WILL NOT happen this time as the currently affected site is huge, and would take days to rebuild the structure, permissions, databases, etc.

I would really like to uninstall Plesk, but it has great features like when you press 'STOP' on the tray icon for it, it causes the whole server to be inaccessible thus spawning a 9pm service call to my datacenter to go physically reboot (as has occured tonight, as the final insult in a long day of terror). PLESK IS EVIL SOMEONE HELP !

In IIS you check the option to allow windows to manage
the password. This means that you don't need to enter a
password at all.

I don't know if Plesk has the same option.

Also, have you turned off anonymous access. Again a simple
tick box in IIS

Hi,

No I cannot see anything in Plesk regarding anon user access.

In IIS Manager under the particular site properties, anonymous user access is most definitely on.

I tried creating a new IUSR account, assigning it to the appropriate groups, and still get the password prompt. I even tried assigning 'Everyone' and giving Full Control on everything at WWWRoot and below. just for a moment to see what would happen: nothing, still a password prompt.

If it is a windows 2003 server, make sure that IWAM_machine has
the same permissions as IUSR.

It seems to need them

The IWAM account is present on the whole site, and has Read permissions.

I believe the solution should be to locate this IUSR_Name in the Metabase, and then copy the password from there into the IIS Directory Security setting for the affected site..

I cannot figure out where to find the user account in metabase explorer though, any idea?

##EDIT. I found the Anonymous User Password for the site and copied it into the IIS Directory Security panel. This seems to have stopped the NTFS prompt, however i am getting a 'Directory Listing Denied
This Virtual Directory does not allow contents to be listed.' message now.. all permissions should be correct on the virtual dirs in question..