Using a Mac OS 10.28

I cant change my pawn into a queen is it becaue I am Using a Mac?

I'm using a Mac, though a later OS (10.4.5) - works fine for me. Tried different (newest) browsers?

What browser are you using? Try changing your browser like the above suggestion. It should not be the fault of the operating system itself. Version 10.2.8 is not obsolete, or something. Now, if it were OS 9.x...