Windows 2000 IIS 5 problem

Hi, I've installed php on a windows 2000 platform but I'm getting a very odd problem. When I first hit a .php page, it works great (by the way, I'm using php to access a free table database via DSN provided by the odbc source server.) when I try to reload the page I get a CGI error. So on the first instance the page, with all the database tables comes up great, but when I reload, it says that cgi application misbehaved by not returning a complete set of HTTP headers, and the headers it did return is not listed (no output being generated?). anyway, has anyone encountered such a problem before? thanks for any help, a new php user, Jason