php com ms word Documents-> Open()无效

I'm generating MS Word .docx files with COM (Component Object Model) using Find/Replace method on a template document.

The problem: it works fine on my PC, but I can't get it work on the production PC!! I have same configuration on both computers.

First I instantiate a COM object $word = new COM('word.application'); echo "Loaded Word, version {$word->Version} "; says 12.0. So I deduce everything is ok so far. Something goes wrong on $word->Documents->Open("c:\\test.docx"); command. It look's like whatever I put between the brackets is not passed through. Just the same as I'd put $word->Documents->Open(" ");

On the next line: $word->Selection->Find->ClearFormatting(); I get the error message: "Trying to get property of non-object " and a fatal error after that. It looks like an empty string is passed in Documents->Open() and the COM object is destroyed.

I tried relative, absolute paths, backslashes, double slashes... and it look's like it doesn't have anything to do with it. As well the command $word->visible = 1; doesn't bring word up.

There is more or less the same configuration on both PCs : 1st PC: - win7 Ultimate,32-bit, ms Word 7, same WAMP version 2nd PC: - win7 Professional,32-bit, ms Word 7, same WAMP version

I tried macros on the second PC, like: Documents.Open FileName:="test.docx" etc. and it works fine. I have no idea what is different on the second PC and what could possibly be the cause.