I was having trouble with PHP4.0.0 crashing (I later realized I was leaving persistent db connections open), so I upgraded to 4.0.1 after reading it was more stable in Win32 environments. I keep all of the php files in my cgi-bin. I removed all of the existing files (php.exe, php.ini, and a handful of dll's), and replaced them with the 4.0.1 files. I configured php.ini; the only changes I need to make for my system is to enable magic_quotes_sybase. After parsing any of my scripts, the only thing it would output to the browser was the ASCII contents of the file php.exe (like if you were to open php.exe in a text editor). I replaced the 4.0.1 files with the 4.0.0 files, and it worked fine again. I am running Apache 1.3.9 on Windows NT workstation sp6 and SQL Server 7.0. I didn't try php 4.0.1sp2 because this wasn't addressed in the change doc.