I have this function I've been using to find a bug in my script, but that now appears to be a bug in PHP itself:

function debug($msg)
{
   echo '<b>DEBUG</b>: ' . $msg . '<br/>';
}

I have this function on a page with a form on it. When I call this function when the form is not submitted yet, everything goes fine, but when I call it when I have submitted the form, it goes fine a couple of times but then it gives me this message, saying that the variable is undefined:

Notice: Undefined variable: msg in f:\website\public_html\test\form.php on line 51

Line 51 is the "echo '<b>'..." line in the function above. 

I get simillar strange behaviour when I create a new object and then in the object's constructor I access $this and it also gives me an undefined variable error.

I get this behaviour with both Apache 2 (2.0.40) and Apache 1 (1.3.26), with PHP versions 4.2.0 and 4.2.2. I haven't tested it on any other versions, but I think it will behave the same.

Sometimes Apache 2 crashes on this, other times it would display the errors. After having this a couple of times, my computer even restarts by itself for some reason!

Apache 1 always displays the error message.