4.2.1 installation under WIN2k with IIS - Extensions just won't work

All I installed the 4.2.1 release over my 4.0.6 release (and had major fun getting all of my variables working again!) BUT I can't get php_gd.dll to load as an extension. I have added every combination in the extensions_dir line, including the 4.0.6 entry which worked fine. All I get is an nable to load module error on the client browser and on the systems console. I've copied dll's 'til I'm blue in the face but am getting no-where fast. any thoughts would be gratefully appreciated. Best Wishes, John Brown. Host Europe System Administration. Host Europe PLC john.brown@hosteurope.com