global $myvar;
unset ($myvar);

// works.

-------------------

// ($unsetvar was set to "foo" somewhere in the script, and is global

global $unsetvar;
echo $unsetvar; // => "foo"

if($unsetvar == "foo") {
	echo "unsetting myvar";
	global $myvar;
	unset($myvar);
}

// this will echo "unsetting myvar" but NOT unset the variable!

// it seems the bug occurs when trying to use unset inside a structure that is doing some kind of test on a variable brought into global scope (even though the variable has the orrect value and the if statement succeeds!). It's not the if statement, because if(1) works.