I do a lot of development on my laptop, both at work and ay home. Both machines are running Windows XP Professional, and have IIS installed. I often get the error HTTP 403.9 - Access Forbidden: Too many users are connected". I have done some digging around this, and found that by default IIS 5.1 on Microsoft Windows XP Professional allows only ten concurrent users connected at any one time.
To get around this, you first need to change your default windows script host to cscript.exe:
cscript //h:cscript
Then you can increase the connection limit to 40. it can't be increased beyond 40 as this is a hard coded windows limitation:
c:\inetpub\adminscripts\adsutil set w3svc/MaxConnections 40
I would then re-set your default windows script host back to it's default of WScript.exe, by:
cscript //h:wsscript