hello, i need little help.I'm learning blender by my own. watching videos on youtube. version i'm using is Blender 2.6. when i open the blender. it shows the same screen as shown in many tutorial. but when i click and drag on it , it doesn't seem to rotate the object (cube).Instead, where ever i click on the working screen, this black cross with red and white circle appears. though the numpad keys to rotate are working properly. what should I do?