The PHP serial class can not read from the serial port on Windows due to some fundamental flaw in how Windows handles the serial port stream.
I think you have that backwards. Windows handles serial port activities with properly written aplications with no problems. As far as I know the PHP developers did not include hardware I/O in their application. PHP is a file/text/database type of application. Windows will treat a com port as a file and write to it when requested. Note that the "f" in fopen and fwrite probably stands for "file".