OK this is odd. I have just installed two fresh copies of 6.2. Clean everything (one prod, one dev). In both instances the installer gives me a warning httpd did not start. When I restart the server and look in the <nim>/probes/service/httpd directory I find httpd.exe is missing. A re-deploy from the archive fixes it.
The site I am at can not de-active antivirus, well not without a weeks worth of paperwork and I am only here a week. Does this sound like a likely cause/effect?