IIS4.0 locking PHP files

Bug: There is an intermitent error about php4ts!_efree causing an unhandled exception error with the Beta3 ISAPI module in IIS4.0 (NT4/SP6). The script I am using is using classes, I saw another post in the archives about class bugs and am not sure if they are related. Also, It seems that whenever my IIS4.0 reads a PHP file it leaves the file locked and I cannot save over it until I shut down the IIS Admin and Web Service. I was experimenting with ASP pages a few years back and had the same issue with ASP pages being locked, but that was different server entirely - unfortunately I never bothered to find out why they were locked. I have to imagine there is something basic that I am missing, anyone have any tips for me? Michael Kurth