Hi there, I was getting the same error and tried many solutions found from forums with no luck. I was trying to get a website working and carelessly changed some settings in IIS. If you havent found a fix yet, try this. Note these steps are from XP pro, win2000 should have similiar steps.
Open IIS console, expand to the Default Web Site folder and right-click, select Properties. Select the Web Site tab. In the Web Site Identification area, make sure (All Unassigned) is selected from the drop down list. I had my IP address listed in this drop-down box and it was using the IP instead of localhost. Hope this helps.