PHP4 B4: MySQL not loading for ISAPI dll

I have installed the PHP4 beta 4 binaries from php.net. PHP4 is installed in D:\IIS\PHP4. php_mysql.dll is in D:\IIS\PHP4\Modules. libmysql.dll is in the path. C:\winnt\php.ini has the extension dir set to "D:\IIS\PHP4\Modules" and has "extension=php_mysql.dll" enabled. php.exe works perfectly. The ISAPI version ignores the MySQL extension entirely. All of the other PHP functionality I've tried works as expected. If I try loading it manually using dl("php_mysql.dll"), I get Fatal error: Unable to load dynamic library 'D:\IIS\PHP4\Modules/php_mysql.dll'<br> The specified module could not be found. The file, of course, does exist and Everyone has Full Control over it. Any ideas? I've looked through the PHP developers list archive but didn't find anything which seemed related. Here's a FILEMON trace of the activity as php.ex loads: IRP_MJ_CREATE D:\IIS\PHP4\Modules\php_mysql.dll SUCCESS Attributes: Any Options: Ope IRP_MJ_CLEANUP D:\IIS\PHP4\Modules\php_mysql.dll SUCCESS IRP_MJ_CLOSE D:\IIS\PHP4\Modules\php_mysql.dll SUCCESS FSCTL_IS_VOLUME_MOUNTED D:\IIS\template-demo.digitaria.com SUCCE SS FASTIO_QUERY_OPEN C:\WINNT\System32\odbcint.dll SUCCESS FSCTL_IS_VOLUME_MOUNTED D:\IIS\template-demo.digitaria.com SUCCE SS FASTIO_QUERY_OPEN C:\WINNT\System32\odbcint.dll SUCCESS FASTIO_QUERY_OPEN C:\WINNT\System32\odbcint.dll SUCCESS IRP_MJ_CLEANUP C DASD SUCCESS FASTIO_QUERY_OPEN C:\WINNT\System32\odbcint.dll SUCCESS FASTIO_QUERY_OPEN C:\WINNT\System32\odbcint.dll SUCCESS FASTIO_QUERY_OPEN C:\WINNT\System32\odbcint.dll SUCCESS FASTIO_QUERY_OPEN C:\WINNT\System32\odbcint.dll SUCCESS FASTIO_QUERY_OPEN C:\WINNT\System32\odbcint.dll SUCCESS IRP_MJ_CLEANUP C DASD SUCCESS FASTIO_QUERY_OPEN C:\WINNT\System32\odbcint.dll SUCCESS FASTIO_QUERY_OPEN C:\WINNT\System32\odbcint.dll SUCCESS FSCTL_IS_VOLUME_MOUNTED D:\IIS\template-demo.digitaria.com SUCCE SS FASTIO_QUERY_OPEN C:\WINNT\System32\odbcint.dll SUCCESS FSCTL_IS_VOLUME_MOUNTED D:\IIS\template-demo.digitaria.com SUCCE SS FSCTL_IS_VOLUME_MOUNTED D:\IIS\template-demo.digitaria.com SUCCE SS IRP_MJ_CREATE D:\BIN\LIBMYSQL.dll SUCCESS Attribu tes: Any Options: Open IRP_MJ_CLEANUP D:\BIN\LIBMYSQL.dll SUCCESS IRP_MJ_CLOSE D:\BIN\LIBMYSQL.dll SUCCESS Here's a FILEMON trace of the activity as inetinfo.exe loads the php4isapi DLL: IRP_MJ_CREATE D:\IIS\PHP4\Modules\php_mysql.dll SUCCESS A ttributes: Any Options: Ope IRP_MJ_CLEANUP D:\IIS\PHP4\Modules\php_mysql.dll SUCCESS IRP_MJ_CLOSE D:\IIS\PHP4\Modules\php_mysql.dll SUCCESS This is the last mention of php_mysql.dll that will appear in the log.