upgrade 4.3.9 to 4.4.1 on windows XP Pro sp1, Apache2.0.52

My ISP wants me to upgrade to 4.4.1 to improve defences against spammers so I downloaded the 4.4.1 windows zip file and installed it manually making the relevant changes to httpd.conf file and the php.ini file as well as the windos Path variable. In fact I made an independent installation of 4.4.1 in its own directory. I've had 4.3.9 running on this apache2 server using databases under MySql with no problems for at least a year. 4.4.1 keeps bringing up a windows dialog "Apache HTTP Server has encounted a problem and must close ...." but otherwise seems to be installed and producing the web pages + their Mysql data correctly. The phpinfo() screen seems to read ok. Everytime I go back to 4.3.9 everything works fine like it always did. Everytime I go forward to 4.4.1, I get this message box from windows (wanting me to report everything to Microsoft) every time I enter a page request. Although the page displays correctly. Did I miss something or should I give 4.4.1 a miss ?