variable gets lost in function problem again...

Sorry all but I really need to figure this out. Here's a recap of my problem: I have an two dimensional array that is returned from code from an included file. I'm assigning parts of the array to variables ( $variable = $array["key"]["value"]; ). This works fine and can be printed until I send it through a function eg. ( ereg_replace(" ", "_", "$variable"); ). After this, $variable is blank. I don't think it's my code because substituting a text string for the array data (eg. $variable = "this is some text";) works just fine. It has something to do with the assigning array data to a variable or perhaps that the data comes from an included file... This could be a bug in PHP? Does this sound familiar to anybody? I can't figure it out! Any help would be much appreciated. Thanks, Spunk