note 17050 rejected from function.fputs by zak

I already spent hours with trying to build a php-class which contains a method which writes data to a file. the *really* strange thing is, it doesn't write any new-line breaks or other control chars (\n,\r,\t,...) to the file, it just ignores those chars. If i use that code in a normal script (without the class around it) it works just fine. Please... does anybody know how to fix this? is it a php bug?