Enabling php_gd.dll in v.4.0.6 on Omnihttp and Win XP

OK, I give up. I've installed Omnihttpd server v.2.09 with PHP 4.0.6 built in. Everything works OK till I try to enable the php_gd extension. I've placed the dll directly under c:/httpd/php/ for now and put this as the path in the php.ini file in Windows folder. I've tried forward and backward slashes, and the path is in quotes. I always have a trailing slash. I've uncommente the line in php.ini referencing the dll. But when I run a script I get: First: " The procedure entry point add_assoc_long could not be located in the dll php4ts.dll" Then: "Unable to locate dll 'c:\httpd\php\php_gd.dll' - the specified procedure could not be found". I've just rebuilt having moved to Windows XP. Had all this working OK previously (on Me) so find it hard to understand what's going on. But looking through the archives others have had similar problems (though I haven't found an answer there that I haven't already tried). Any help apreciated. Alan Hale