strange loop counter behavior ... bug?

I am converting a list of keys to names (strings)

This works:
integer t=0;
integer i=0;
for (i=0;i<llGetListLength(GL);i++);
{
temp=llKey2Name(llList2Key(GL,t));
GNL=llListInsertList(GNL,[temp],t);
t++;
}

This doesn't:
integer i=0;
for (i=0;i<llGetListLength(GL);i++);
{
temp=llKey2Name(llList2Key(GL,i));
GNL=llListInsertList(GNL,[temp],i);
}

This doesn't:
integer t=0;
while (t<llGetListLength(GL));
{
temp=llKey2Name(llList2Key(GL,t));
GNL=llListInsertList(GNL,[temp],t);
t++;
}

Huh? Apparently i is counting but not allowed to be used within the for loop

I have not taken the stability dl nor have I ever seen behavior like this before.
Is it becasue there is only one element (at index 0) in the GL list?
Still shouldn't be happening ... ever ... afaik

<edit>Yup, I'm asleep. Thanks Jillian *smacks self*. For whatever reason I read to OP as regarding a compile error.</edit>

Works as expected in Second Life 1.6.11 (3) Aug 22 2005 09:08:16. Don't suppose you could paste the entirety of a script that exhibits the behavior? If it is some archacic bug, I rather suspect it will be triggered by the earlier declarations. I just tried:

default
{
    touch_start(integer total_number)
    {
        list GL = [ 1, 2, 3, 4, 5];
        list GNL;
        string temp;
        integer i=0;
        for (i=0;i<llGetListLength(GL);i++);
        {
            temp=llKey2Name(llList2Key(GL,i));
            GNL=llListInsertList(GNL,[temp],i);
        }
        llOwnerSay((string)i);
        llOwnerSay((string)GL);
        llOwnerSay((string)GNL);
    }
}

That first ; after the for() should not be there:

integer i=0;
  for (i=0;i<llGetListLength(GL);i++)
  {
  	temp=llKey2Name(llList2Key(GL,i));
  	GNL=llListInsertList(GNL,[temp],i);
  }