Fatal error : unable to open.. NT4.0-IIS4.0-PHP3

Hi all, I'm new to php, I've installed php 3.0 according the instructions in the manual on the following system : Win Nt 4.0 Sp6 - IIS 4.0 + I Res Kit + Hotfixes Copied files to winnt/*.* - Updated registry .... When I run my testfile from the php install dir .. php phptest.php, I get the expected results and no errors... When I access the same testfile from an url I get : Fatal error: Unable to open ???????????????p in - on line 0 No input file specified. The code in the test file is a simple echo .... The .php, .php3,.... extensions are mapped within IIS... The php3 dir has special directory rights (execute,...) I suspect the test file can't be found ...? Can anybody give me a clue on this one ..... Any help greatly appreciated,..... TIA Roger