PHP COM encoding problem

Hi everyone, I have quite a problem with a COM-Object in PHP. Following Situation: I have a COM-Object that connects to a UNICODE-encoded database, reads certain texts and returns them to PHP, where I process the text and send it back to the database via the COM-Object. Unfortunately I have to use the COM-Object and can not connect directly to the database. My problem is now, that there seems to be an encoding-problem between the COM-Object and PHP. For example I have a letter that looks like an "i", only without the dot above it. When I read a text containing this letter from the COM-Object, I get that letter returned as a normal "i". I have tried different internal encodings in PHP, but with no effect. When I read the original file with these letters from the filesystem, PHP handles it perfectly, also in the database the letters are correct. It can't be a problem between the COM-Object and the database, because when I do the same thing using C# it comes out as it's expected, but somehow I have to get it working in PHP. Does anyone of you know that kind of problem and maybe a solution to it? Greetings Calle