I just downloaded and installed php4.0.1pl2 for windows on IIS4.0 yesterday.
Today the php files started out fine, but then after a few refreshes, it gave me first an unable to select database error, then unable to redefine function, then every single php page gave me 'PHP has encountered an Access Violation at 01A2CE18' and sometimes a nesting too deep warning...but this happens on any page with the phtml extension, even if it doesn't have any php commands.  I tried restarting the server, and the pages worked fine again, but then after a few minutes they started crashing again.