NSMutableString *string = [[NSMutableString alloc]initWithString: @\"http%3A%2F%2Fsupport24hour.com%2Fworkplace2%2Fbuttler%2Fimage.php%3Fwidth%3D534%26height%3D256%2
Hmmm... how about printing out string before you turn it into an NSURL? Does it look as you'd expect it?
Also: replacing "+" with a Space OR do you actually want to remove it?