Wait!

I have run across this before, and it was easily solved by unchecking the "HTTP Keep-Alives Enabled" on the "Web Server" tab of the properties window. ISTR that that box is checked by default as it decreases response time for small numbers of connections.

In my experience, the 10 simultanious connections goes way further than most people expect, as they are each servered in fractions of a second. If you have that checked, this will likely fix your issue so that you don't have to do an OS reinstall. (Unless you really do have a massive, massive amount of people hitting your box.)

Something to try, at least.

John