Php 4.3.10 cannot find php4apache.dll

Sorry if i've double-posted, but i believe i had some improper smtp settings and i think i have to re-post... Just upgraded to 4.3.10 on Apache 1.3.31 running on a Windows XP SP1 workstation (for testing). When i tried to restart Apache, i got the following error in the application log: "...Cannot load c:/apache13/php/sapi/php4apache.dll into server: (126) The specified module could not be found..." Php4apache.dll definitely exists at that location. I am able to prevent the error by replacing the newly-installed .dll with the same file from the old installation. I am wondering if i am asking for trouble doing this? TIA, Jerry