I have a listbox being populated from a SQLDATA pull, and it pulls down some columns that i dont want like OBJECT_dfj, OBJECT_daskd. The key is all of these being with OBJE
The problem here is that you're changing your enumerator as you remove items from the list. This isn't valid with a 'foreach' loop. But just about any other type of loop will be OK.
So you could try something like this:
for(int i=0; i < listBox1.Items.Count; )
{
string removelistitem = "OBJECT";
if(listBox1.Items[i].Contains(removelistitem))
listBox1.Items.Remove(item);
else
++i;
}